Those with a yen to spend are finding that the cost of foreign goods, from cars to cameras to wine and cheese, is racing upward as the value of the dollar continues to fall against some foreign currencies.

In the past six months, Washington area merchants say, the price of French cognac has risen $5 a bottle, Japanese watches have increased $10 apiece and the sticker prices on some luxury automobiles from Germany have soared $5,500.

Tony DiLorenzo of Pohanka Honda in Silver Hill said that since December he has passed on $1,400 in price increases to buyers of the popular Honda Accord LX. "Before, it was only going up $200 a year," he said. "It hasn't really helped business, I'll tell you that."

The weakening of the U.S. currency overseas means that it takes more dollars to buy foreign products. That increase then shows up on the price tags in U.S. shops.

It has affected such products as electronic entertainment equipment, eyeglass frames, vitamins and antibiotics, pottery and dishes, gourmet foods, sewing machines, ski equipment and jewelry.

"The price of gold, especially Italian gold, has gone up," said Henry Baker, buyer for the Glitters jewelry shop on Capitol Hill. A gold watch that sold in December for $90 is now $100, he said, adding, "The only thing we do, like everybody else, is pass it on to the consumers."

In some cases, merchants are deciding not to restock and are promoting less expensive American goods.

Steve Mark, a wine specialist at J.J. Mutts of Capitol Hill, said that much of the store's inventory was purchased before the dollar started to plunge and that the shop has been able to hold down prices. But white French burgundy now selling for $9 a bottle will cost about $14 if he reorders it, Mark said.

He probably will not. Instead, Mark said, the store will start promoting California wines. "There are alternatives," he said.

Bill Alterman, chief of the U.S. Bureau of Labor Statistics' import/export price index, said prices on imported products started inching upward more than a year ago in response to the weakening dollar.

But overall, statistics for the first three months of 1986 show that the upward swing in wholesale prices for imported goods has not been as dramatic as the dollar's plunge.

"We have been seeing an increase . . . for selected categories of imported goods," said Alterman. "But the price trends have been somewhat uneven."

Increases are most pronounced, Alterman said, in products from Japan, West Germany and other parts of Western Europe, where the value of the dollar has fallen as much as 30 percent since September.

At Martin's of Georgetown, the decline of the dollar has led to the first significant price increases at the store in recent years, according to owner E.F. (Shawnee) Uberman.

"Prices haven't gone up in a good three years. But this year, they did go up," she said, noting that the prices of the popular Baccarat crystal and Ceralene porcelain have increased between 5 and 20 percent.

Imports valued at $343.6 billion were brought into the United States last year, accounting for one-fifth of all goods sold in this country. For merchants who sell mostly foreign-made goods, the fluctuating exchange rate is a serious concern.

Eighty-five percent of foreign cameras sold in the United States come from Japan, and local camera retailers have been among the hardest hit.

"The wholesale prices are changing every week," said Jeff Lee, advertising manager for the Ritz Camera store chain.

At the Ritz Camera Center at Spring Mall Square in Fairfax, sales manager Cathy O'Brien said the prices of Japanese cameras have gone up at least $10 since the beginning of the year. The company's current sales brochure contains a note apologizing for fluctuating prices. The popular Minolta Maxxum was $319 last fall but now sells for $339, O'Brien said.

"You can't buy an organ or a keyboard that isn't imported, even with standard American names on them," said Carole Pascoe, a sales staff member at Jordan-Kitt's Music Center in Springfield Mall. Prices of imported pianos and electric keyboards are expected to rise almost a third by the end of summer from last year, she said, while domestic piano prices have gone up only about 10 percent.

The price of a Yamaha electric keyboard has risen $400, to about $2,600, according to Pascoe, and at $6,990, a Kawaii grand piano costs about $1,000 more than last year. Customers are noticing the soaring prices on "big ticket" items, she said.

"They'll look at an electric keyboard and come back in two to three months and it's a couple of hundred dollars more, and it's hard for them to understand why it's going up so fast," she said.

At Georgetown Electric in Northwest Washington, owner Henry Reuwer said, "All the VCRs have gone up 6 percent since the end of January, and they'll be going up again this month."

At J.J. Mutts, expensive French liquors have risen by $2 a case since January, but the cost of imported German beer in the wine shop has remained steady. Owner E. Lamar Shade noted that prices are affected by other factors, including federal tariffs, annual cost increases and supply and demand.

Some analysts say that foreign companies may try to keep prices from rising too much because they fear competition from goods made in the United States and elsewhere. The prices of products from newly industrialized countries of the Far East such as Taiwan and Korea, whose currencies have remained stable against the dollar, are not increasing.

Analysts say that will make some of those nations' products, such as televisions, radios and toys, more attractive to consumers than the traditionally popular Japanese goods. The difference between cameras of similar quality from different parts of Asia, for example, could be as much as $40, said Ritz Camera's Lee. "It's not so much that the Korean product is cheaper, it's less expensive," he said.

Alterman of the Bureau of Labor Statistics noted that another import from the Far East -- clothing -- is expected to be spared. "Apparel has a life of its own," he said.