The organization of Ludlow (Pete) King III is building clustered, three- and-four-bedroom town houses off Rte. 1, just below Fort Belvoir. All are priced under $50,000. The site is part of the original tract that was developed with clustered condominium dwellings of smaller size. But the King people switched signals and converted siteson which foundations had been poured into two-and-three-level town houses without basements. The new models are being sold as "fee-simple" individual ownership units with an interest in some common areas, including a pool and tot lots. "We were pioneers in town house condominiums," said executive vice president James L. Brehony, "but we see the market now being stronger for larger dwellings with personal ownership of the individual dwelling. And we have space averaging about $30 a square foot." The largest, most expensive model is a Cape Cod end unit with two small bedrooms on the first floor, in addition to living room, dining room and kitchen and two big bedrooms upstairs.

Shops and a bistro dominate the first floor of the Crilley Warehouse, a $1 million restoration project in Old Town Alexandria. Realtors Nancy Macklin and Marilyn Hansen and architect Michael Reddan have made as the centerpiece of the old building an atrium with an original supporting member through the center and an attractive stairway. Reddan's office is on the second floor along with a Macklin-Hansen space and a spiffy restaurant. The third level is a complex of 27 small executive offices developed by Roger Machanic, who also builds town houses. The idea is to provide working space for a variety of tenants. Rents range from $175 to $375 a month. Some spaces have natural brick walls and all reflect the heritage of the warehouse, once the repository of huge amounts of distilled spirits.

Transfers: New York Timesman James B. Reston, is one of the buyers of a Kalorama Square town house in Northwest. It cost $192,500 . . . And Wiley T. Buchanan III paid W. O'D. Donahue $202,000 for a dwelling at 3343 P St. NW.

Hammer, Siler, George Associates, a real estate research firm, says some 600 town houses and condominium units are likely to be started soon by a half dozen developers here. One of the largest projects, now in a developmental stage, may emcompass 180 units on a site near Trinity College. And there are also indications that several large apartment projects such as Congress park, Camp Simms and Parkside, might be marketed before long for redevelopment.

Sales agent Dorothea M. Gillen, a camera enthusiast, had her first helicopter ride recently when she decided to photograph the Dr. James L. Hooper 20-acre estate that was listed by her firm, Flaherty, Inc., for $395,000. Gillen's pilot was fellow agent Chuch Riel. She made the color photos but captured mostly trees and landscaping. "Hanging out, with benefit of one strap, to snap pictures is quite an experience for the mother of grown children," she said.

D.C. Councilman John C. Wilson, a resident of the St. George apartments at 21st and N streets NW, was a guest this week at a meeting of the Washington Residential Development Coalition, a group of individuals interested in redoing older housing in the city. Wilson applauded their private enterprise efforts in upgrading the city's housing stock but he said that residents of rental housing under rehabilitation for sale should have an opportunity to buy. "The right of first refusal means nothing if you have no money to buy," he said. "Ownership is always a struggle for most people. But some tenants with the zeal for ownership deserves an opportunity and I hope to have the city create a $5 million loan fund to help them do it."