A search by the U.S. Navy for $500 million in new digs has churned real estate developers into a frenzy. But don't look for the Navy to be dropping anchor in your town unless you live in Northern Virginia.

The 16,000 employes of the Navy's sea, air, space and supply commands are scattered throughout 16 office buildings in Crystal City, and Virginia congressmen are determined to keep an iron grip on that economic prize. The last time the Navy got the itch to move was 1981; the plan was to consolidate commands at the Washington Navy Yard. Virginia congressmen put up such a squawk -- cutting off all the appropriated money for the project -- that the move had to be abandoned.

For that reason, the only real estate developers with reason to hope are those in the Northern Virginia suburbs that border Washington. The Virginia lawmakers don't mind a move out of Crystal City as long as the Navy remains in the neighborhood.

When the deal is done, it could be a trend-setter for the government, because the Navy wants to lease office facilities with an option to buy, which could mean paticipating in a joint venture with a private development partner. That's a big step for government, which usually moves in only as a renter.

If the joint venture works, it might spread like a multibillion-dollar wildfire across the land wherever the federal government puts down roots. Already the Navy is quietly looking for a similar deal in San Diego, the home port of its Pacific fleet.

The scattered Navy commands in Crystal City now occupy about 2.1 million square feet near National Airport. What the Navy wants is a staggering 2.5 million square feet of consolidated office space by 1994. That is a tall order, but still short of the Pentagon building's 3.7 million square feet.

The Navy has followers that sweeten the deal. Wherever the Navy offices go, an estimated 7,000 related jobs in private industry are bound to follow to be close to their government sugar daddies. That's big business by anyone's books.

The General Services Administration, the federal government's real estate agent, plans to award new leases next October, which is a year before the Navy's current leases expire. Quietly soliciting bids with an option to buy, the GSA has had at least 17 offers.

Arlington County, which includes Crystal City, is scrambling to keep the Navy from weighing anchor. A 1985 study found that Navy leases and work account for about 5 percent of the county's annual budget, 26 percent of its leased office space and 19 percent of its jobs.

Despite a GSA requirement that the Northern Virginia site be no farther than one mile outside the Beltway, the Navy may consider attractive projects farther into the Virginia countryside.

An official in neighboring Fairfax County told our reporter Jennifer Smith that he could quickly tick off at least five undeveloped sites in his county that would be suitable, not to mention developed sites. At least two proposed projects in Alexandria are also in the running.