At $7, the wine would be worth trying. At $5, it would be a good buy. At $2.50, it's a gift. That's the average price around town for the '79 Merlot, Trakia. It's hard to find a $20 wine with a $2 price tag, as every weekend shopper knows, but in these inflationary times the people at Trakia have come pleasantly close. How do they do it?

The answer may not appeal to most of us in America: it's called Socialism. Trakia is a brand name for the wines of Bulgaria. From start to finish, the wine industry is controlled by a government agency, Vinprom, which orchestrates the whole Bulgarian wine show. The grapes come from collectively run vineyards. The wine is made in 18 cooperative wineries around the country. Prices at every level are controlled by Vinprom, including the exports, which are handled by a subsidiary agency, Vinimpex.

The idea of exports, or bottled wine at all, in Bulgaria is comparatively new. Until 1878 the Moslem Turks, masters of the Balkans, discouraged any trading in wine. And until 1944 there was no serious wine industry, simply because there were no bottling facilities. Today, Bulgaria is the world's third largest exporter of bottled wine.

Most of it is sold within Eastern Europe, but the Western world is becoming increasingly important. Despite the different brand names for the Bulgarian wines that turn up in Japan, Australasia, Britain or Canada, they are all produced and shipped by Vinprom. Trakia, which is an exclusive name for the American market, is a fairly recent development.

Four years ago, Vinprom and its U.S. distributor did some homework. They sent Prof. Maynard Amerine off to Bulgaria to advise the local enologists on the style of wines suited to American palates. Then Vinprom came up with the brand name Trakia, or Thrace. Thrace was a vine-growing region when Alexander the Great came rampaging north from Macedonia. The modern Bulgarians have honored his legendary interest in wine by placing his profile on the Trakia label.

The formula for these tailor-made wines was that the whites should be light, clean and marginally fruity, that the reds should be smooth, and above all that prices should be competitive.

Ten years ago, Hugh Johnson wrote in his World Atlas of Wine that the Bulgarian whites were better than the reds. On the evidence of recent Trakia releases, that's no longer true. Not that there's anything wrong with the whites, a '79 Chardonnay and an '80 Blanc de Blancs. The Chardonnay, which includes a little aligot,e, is light, fairly dry, with a sharpish finish. The Blanc de Blancs, a new addition to the range made predominantly from the misket, a native grape, is again light-bodied and is intentionally much fruitier. All the Trakia wines are the same price, about $2.50, and at that price the whites are fair value.

But the bargains are in the reds. The '77 Cabernet Sauvignon, which contains 30 percent merlot, is medium bodied, earthy and, after two years in large wood vats, is smooth and ready to drink. The Merlot, which in turn contains 30 percent cabernet sauvignon, won the top award in a recent New York competition. It is enjoyable drinking now and has enough chewiness and fruit to age longer. I don't want to oversell the wine. It's not Petrus, but it does have some complexity and style. And for every bottle of '79 Petrus, you can buy two cases of '79 Merlot, Trakia.