Herring Creek Farm, the storied and richly diverse Great Plains farm in the rural coastal perimeters of Edgartown, is now set to be sold for a record price to an eclectic group that includes two nonprofit conservation organizations and two private buyers.

A fresh plan is also now on deck for the 215-acre farm that envisions a limited home development around the Edgartown Great Pond and Crackatuxet Cove, coupled with a pioneering conservation project on the large sweep of farmland in the east and central fields.

Farm owners Neil and Monte Wallace have not revealed the sale price, but it is understood that the final price is roughly $45 million.

Owned by the Wallaces since 1969, the former working farm has been at the center of the longest and most divisive development battle in the history of the Island.

The conservation sale agreement is still incomplete, and the key to the agreement lies in approval from the descendants of the late Benjamin Cohan who hold a right of first refusal on the farm.

"We are talking and we are hopeful - but we are not there yet," said Eric Aldeborgh, a spokesman for the Cohan descendants, in a statement released yesterday.

The covenant held by the Cohan descendants restricts any sale of the farm until the year 2010.

"We are listening. My family's agreement with the Wallaces is an ace in the hole to prevent helter-skelter development of the farm. Before we give up that card, we must be sure of the limited nature of any future development . . . and unwaveringly confident of every proposed steward of this special place," Mr. Aldeborgh said.

Spokesmen for the farm said this week that a closing date is set for June 29.

If the sale goes through, it will mark the largest real estate transaction in the history of the Vineyard and, from the Wallace brothers, possibly the largest conservation gift from a single family in the history of the commonwealth.

The conservation gift is the difference between the sale price and the development value of the farm. A 33-lot residential subdivision was approved for the farm property by the Martha's Vineyard Commission last year.

"This entire initiative may very well serve as a prompt for others. I certainly hope that it will have an overarching global impact, and it should. There are so many important values at stake," declared Stuart Johnson, the chief spokesman for the Herring Creek Farm Trust, this week.

"We as a community can choose any future we want. We don't have to face the future with ponds that are declining and loss of the landscape we love. We can get it back," declared Tom Chase, director of the Massachusetts Islands program for The Nature Conservancy.

"This is a wonderful collaboration, a fortuitous coming together of people, and the Herring Creek Farm is an open palette bounded by water. We have so many opportunities," said John Curelli, the executive director of the FARM Institute.

If the sale is completed and the new plan is approved, The Nature Conservancy will own outright nearly half of the farm, and will launch the largest sandplain grassland restoration project in the history of the international conservation movement. The project will involve converting the entire 62-acre east field to sandplain grasslands and restoring rare native plant communities like the bushy rockrose and Nantucket shadbush.

The new plan for the farm also includes the inaugural project for the FARM Institute, a new Vineyard conservation organization dedicated to agricultural education and preservation. FARM stands for Farming, Agriculture and Resource Management.

The private buyers are Roger Bamford and his wife, Denise Lahey, California residents whose business affiliation is with Oracle, a computer company headquartered in the San Francisco Bay area; and late night television comedian David Letterman.

Mr. Bamford and Ms. Lahey plan to buy Neil Wallace's house, while Mr. Letterman plans to buy Monte Wallace's house. Mr. Letterman has rented one of the Wallace homes for the last three summers.

The primary capital for the complicated purchase will come from Mr. Bamford and Ms. Lahey.

Indirect capital contributions will also come from the FARM Institute and from Mr. Letterman's real estate company, managed by his business associate David Peters. Named MV Regency Group, the company plans to buy four lots on the farm and then sell two, and possibly three of the lots to defray the purchase cost.

"It's exciting to see private parties, conservation groups and property owners working together to help preserve such an important Island resource," said Tom LeClair, a Realtor and partner with Gerret C. Conover in Conover Real Estate in Edgartown. Mr. LeClair represents Mr. Letterman's purchase group.

"You might want to say it's being developed, but we think it's being preserved," he said.

"We are excited about the ultimate preservation of the farm and the conservation activities that will occur as a result of this collaboration," said Mr. Peters.

The announcement this week about the planned sale of the farm signals a distinct new chapter in the tortuous story of the Herring Creek Farm, a story that is marked by 11 years of development plans, contentious lawsuits and millions of dollars in legal fees.

In recent weeks a scattering of gossip column press reports have been published about the sale of the farm, calling Mr. Letterman the savior.

In fact Mr. Letterman is only one party in an extremely complicated deal. The deal involves a number of transactions all at once. Here is how it is expected to work:

* Using unrestricted gift money from Mr. Bamford and Ms. Lahey, The Nature Conservancy will buy the entire 215-acre property from the Wallaces. The Conservancy will place a conservation restriction on the property, and will retain ownership of 102.2 acres (the east and central fields).

* The Conservancy will then sell two lots, including Neil Wallace's house and another small house known as Movius, to Mr. Bamford and Ms. Lahey.

* The Conservancy will sell the rest of the property to the FARM Institute. The institute will retain ownership of about seven acres, including the farmhouse and farm buildings. The institute will also lease a portion of the central field from The Nature Conservancy for farming activities.

* The FARM Institute will then sell four lots to the Letterman group, including Monte Wallace's house. The Letterman group plans to sell two and possibly three of the lots to private buyers.

In the end the plan calls for a maximum of 10 lots with 11 houses on the farm. Five are existing houses, and six new houses could be built - four on the Great Pond and Crackatuxet Cove, and two on Slough Cove Road.

Restrictions on the house lots include a 25,000 square-foot development envelope, and no guest houses. The homes will be limited in size to 7,500 square feet.

Mr. Chase said The Nature Conservancy plans to impose an array of other restrictions on outdoor lighting and fertilizer use.

The Conservancy also plans to manage the beach, with a protection program for terns and piping plovers.

"Our mission is biodiversity," said Mr. Chase, who said the sandplain restoration project is intended to join with the adjacent sandplain grassland at the Katama Air Park.

"This is, in terms of dollars, the largest land deal in the history of The Nature Conservancy - credit goes to Roger Bamford and Denise Lahey, who are willing to hear what the message is and get personally committed," Mr. Chase said.

"And if the Wallaces weren't willing to do this deal with us, we couldn't do it, and they are heroes, too," Mr. Chase added.

The intended sale agreement includes a plan to transfer three lots, including the house known as Sanderling, to the Cohan descendants, but this part of the deal is still incomplete.

Development plans for the farm were first filed in 1990, when the Wallaces filed a subdivision plan for 54 houses and a beach club on the farm. Three years later, after an exhaustive review, the plan was rejected by the Martha's Vineyard Commission. Along the way, the Wallaces sued the town to challenge the three-acre zoning limit. After the development plan was rejected, more lawsuits were filed, including an appeal of the 54-lot plan.

That appeal is still pending in court.

Two years ago the farm owners filed new plans for a 33-lot residential subdivision with a private club.

Late last year the commission approved the 33-lot plan without the private club.

When the new sale agreement for the farm is completed, Mr. Johnson said all lawsuits will be dropped, and the 33-lot plan will be replaced with the 10-lot plan.

The new plan will need fresh approvals from the Martha's Vineyard Commission, the Edgartown planning board, the town conservation commission and the board of health.

"This isn't just about saving a place - this is about bringing things back," said Mr. Chase.

"This is what they should have done 10 years ago," said Edgartown town counsel Ronald H. Rappaport, who successfully defended the town in the landmark challenge to three-acre zoning brought by the Wallaces seven years ago. The Wallaces lost the case.

Mr. Johnson said yesterday that the story of the farm can be divided into what he called "old history and modern history." He said modern history began about two years ago on the Vineyard.

"I sat on rocks; I sat on curbs; I sat on benches. And I listened," he said.

"And I talked to the Wallace family. We talked a lot. They encouraged us to think creatively and there was mention of low density.

"And where this entire initiative got its propellant is when the Wallace family called me and said they were prepared to make a major donation to make this vision a reality."

Mr. Johnson said candidly that the deal has been hard. "I always believed it would happen, but I never believed it would be this hard to do - never, ever," he said. And he concluded:

"We are not there yet, but I have reason to believe we will succeed."