An apparently inexhaustible public appetite for expensive condominium apartments and town houses in prestigious urban areas will get another test next spring on Georgetown's fast-changing water-front.

But Marvin Weissberg, a Georgetown resident whose development corporation is at work on a block between the C&O Canal and K. Street NW near Key Bridge, is confident. Weissberg says that the early interest among potential buyers of luxury condominiums and the presale records of nearby redevelopments form the basis of his optimism.

"Here at the Flour Mill, between Potomac and 33d streets, you can see we have two old buildings being redone for office tenants and a complementing new office structure planned for the 1 1/2-acre site," Weissberg said.

"That big hole in the ground (along 33d Street below the canal) will be a six-story new apartment building with only 55 residences . . . The price? Well, we are not taking contracts yet, but the price per square foot will be over $100."

If that figure staggers your financial imagination, be reminded that presales of relatively small town houses and apartments - with features such as exposed brick, circular stairways and skylights, - in the nearby Papermill and Canal House developments were also in that ultra price range. Units there, some of which will be ready in a few months, sold out early.

"We have contract buyers for all the duplexes and town houses for both our Papermill and Western Development's Canal House," said Robert Holland of Holland & Lyons. Most buyers seem to assume that the adjacent - and highly visible - Whitehurst Freeway will be razed eventually.

Concerning that elevated freeway, which connects Key Bridge and K Street on the western end of downtown, Weissberg said that his Flour Mill apartment building was designed by the International Consortium of Architects (ICON) to be above it. However, he conceded that the lower levels of the office buildings will be right up against it.

"If it were turn down, we'd thank God," he observed.

But those who moves into the expensive offices and residences that are to transform much of Georgetown's industrial waterfront will be living with the freeway until a major highway relocation or change is made by the District.

"Meanwhile, lower K Street (under the freeway) continues to be a relatively unjammed avenue for auto traffic and provides good access to these new projects," Weissberg said.

The developer also said that the appeal of his Flour Mill project, which will be completed after the Papermill and Canal House residences are finished, will depend on the mixed use of the site.

"We'll have both new and redeveloped office space in large, attractive spaces near our new condominiums, he said. "That will ensure 24-hour use in a truly modern mixing of business and residential uses. The apartments will be large (1,400 to 3,000 square feet) with dining rooms, large baths - many features identified with custom houses."

"Before 1985," Holland said of the area near the canal and west of Wisconsin Avenue, "it should appear much like a waterfront European village."

ICON architect Peter Vercelli said that Weissberg's Flour Mill project, on the site of two former milling buildings, will incorporate silo designs in both the new office and residential buildings because the originals could not be retained.

"The grain silos had no foundations, only straight footings," he said. "When the mill was operating, they had to becareful how they filled the silos."

The London-born Vercelli, who had a role in restoring historic building ravaged by World War II bombings, said that the 1845-vintage Pioneer building on the northeast corner of the Floor Mill site has brick interior walls and timber construction, including "12-by-12 beams and columns that are semiprecious today."

Weissberg - who is banking on potential office building tenants being willing to pay at least $13 a square foot for spaces with high ceilings, brick walls and old, exposed beams - said that new construction had been delayed by some leakage from the elevated C&O canal. Vice president Arthur E. O'Donnell said that the leaks have been plugged but that all the canal walls should be rebuilt.

While Holland & Lyons, Weissberg and Western Development have leading roles in the new residential, office and commercial changes and restoration north of K Street, the pryramidshaped brick Dodge Center office building (at Wisconsin and K) is getting a new residential neighbor.

Leonard Greenberg and Peter Schwartz head a group developing 12 multistory, contemporary apartments designed by Arthur Cotton Moore. The now $222 Cherry Hill Lane building. Greenberg said, is actually an addition to the Georgetown Residents Club at 1024 Wisconsin. Built by Glena Construction, the nearly completed duellings will be priced from $123,000 to $160,000 Greenberg said six have been said.

Now that developers have circumvented the objections of old-line Georgetown residents and the scruitiny of the Fine Arts Commission on the Georgetown waterfront, they are being asked what the area will look like by 1985.

Well, the old Bayon night club has survived to date and may continue its longevity, it is observed. It is likely to be joined by a discotheque in a Papermill building and by a health club and restaurants in the Flour Mill and by the shopping and other commercial facilities generated by Western Development north of the canal.

Developer-marketer Robert Holland says he looks forward to a new waterfront.

"It had gone downhill from its outmoded industrial era," he said. "There was evidence in some of the old buildings (that were razed or redone) that they had become hangouts for drug users.

"What's being done now should be an exciting new happening, long overdue here. I've seen it in other cities and are confident that our efforts will win public acceptance."

Meanwhile, Georgetowners will be watching. So will many area residents and visitings who recognize that Georgetown is something truly special. Chances are they've heard about it in Kokomo and Keokuk, where they may be hazy on Tysons Corner and Montgomery Village.