Early on the morning of my 45th birthday I found myself in the Punta del Este vacation apartment of a Uruguayan horse trainer named Luis Balparda Arrospide, who was cooking a dinner of spaghetti with a choice of alarmingly rich white sauces for a few close friends.

Most of them were female, young, tanned and lovely in March, the end of Uruguayan summer. They had started arriving about 11 p.m. and were still streaming in the door at midnight, standard supper-serving time in these European-oriented parts.

Arrospide's two-room high-rise apartment overlooks one of Punta's fine beaches, and as the little place got more and more crowded some of us were being pushed out on the balcony into the warm ocean breeze, to make room for new arrivals. The Southern Cross twinkled in a starlit sky.

As each new young woman cleared the doorway, she would make a circuit of the living room, then the balcony, announcing her name to each of the guests, male and female, and puckering for a kiss.

"Maria!" one would say, beaming, and kiss me wetly. "Gabriela!" said the next, drowning me in a sea of black, perfumed hair. Reeling, I cast a glance toward Jim Lutz, an American sailor who was alongside. "Lovely custom, this," he said dreamily, clutching the latest newcomer.

Meantime, Luis was in the kitchen frantically cooking for 16 or so on a two-burner stove. He was a good cook; you could smell the garlic, olive oil and wine simmering away. He started serving just after midnight, but we had to eat in shifts because there were only so many plates. Someone flipped on the TV, which was showing the stupid movie "Three Men and a Baby," with Spanish subtitles.

We all gathered 'round, and I saw Lutz over in a corner, his head in the lap of one Uruguayan beauty he'd met 15 minutes earlier, his hand idly stroking the tanned calf of another and a look of utter bliss on his face after four hard weeks at sea. The headline blinked on in my brain: "Middle-Aged Men in Paradise."

"Hey!" I said, looking at my watch and seeing that the midnight hour had long since tolled. "It's my birthday!" And the ladies rushed over to kiss me again.

As the dollar falls in value and the European Economic Community expands and strengthens, all the old bargain places are drifting away. Spain? Last I looked, the peseta and the penny were roughly the same and the day of the elegant $10 meal was over, no doubt for good.

In Uruguay, though, enough remnants of the Third World hang on that you can still do wonderful things cheaply. And North Americans are enough of a rarity that the locals seem genuinely glad to see you and interested in your welfare.

After two weeks there, covering a sailing race that turned out to be less exciting than anticipated, I had a pretty good handle on where the bargains were.

For my final meal, I stopped in at El Metejon, a downtown parrilla -- the sophisticated South American equivalent of a barbecue. The main feature is a crackling wood fire in a corner with a huge grill banking away from it, bedecked with slabs of beef, chicken, black sausage and pork roasting over the glowing embers.

I ordered the best: a tenderloin beefsteak called lomo, a large mixed salad of fresh lettuce, tomatoes and sweet onions, a Pilsener beer, french fries and an espresso to cap it off.

The white-jacketed waiter was attentive; he mixed the salad dressing at the table and delivered a huge chunk of tender beef aged just so, grilled to perfection and sizzling hot. The bill for this kingly repast? Well under $10, including tip.

Another day I stopped by the seashore in the afternoon to snap a few pictures and spied two tanned gentlemen slurping mussels under an umbrella. One turned out to be Hugo Vidal, president of Punta's Restaurant and Hotel Association, who said the shellfish had been caught the day before by divers just off a little island visible across the sea. Steamed in garlic and wine and served with crusty fresh bread, they were spectacular.

"Tell me," said Vidal as we slurped, "how much are you paying for your hotel here?"

About $45 a day, I thought.

"Too much!" he thundered. "You shouldn't pay more than $30 a night."

So Punta's a bargain. It was all I could do to spend $1,000 in two weeks, including hotel, all meals at restaurants, taxis around town and entertaining a few news sources. I rented a bicycle for a week -- a five-speed in reasonably good shape, for $20. With air fare, the whole trip came in under $2,000.

And what do you get for your money? Two things, guaranteed: warm water in the dead of our winter on some of the prettiest beaches on the Atlantic coast, and a lively, European-style downtown within blocks of the sea that features good restaurants, amusing entertainment and a culture very different from ours at home.

First, the beaches: Punta del Este is at the end of a peninsula that juts into the South Atlantic from the mouth of the Rio de la Plata. One hundred thirty-eight miles across the river lies Argentina, where most of Punta's vacationers come from.

The peninsula, only a few blocks wide, features ocean beaches with surfable waves on one side and protected, bay-like beaches on the other. The wind often blows hard, but there is always a protected side to repair to.

December through March is high Southern Hemisphere summer and high Punta season. The weather is fairly predictable -- sunny, breezy and warm most days, rarely hot with the sea breeze, but occasionally rainy for two or three days as a front comes through. Autumn stretches into April, when the beaches are uncrowded, the water still warm and hotel rates are down.

What to do at the beach? Swim, of course, and admire the maidens, who have developed a swimsuit that defies description. There is a small fleet of sport fishing boats that goes mostly in pursuit of small cod, red drum and something that looks like a croaker. The fee is about $40 an hour and the boats carry up to six people.

One afternoon I rented a windsurfing board for $5 an hour, which was pleasant enough; and there are sea kayaks, small sailboats and pedal boats for the kids at similar rates. Entrepreneurs roam the beaches all day, hustling helados (ice creams) and pastellitos (pastries), and every beach has a restaurant where you can order mussels, espresso or full meals to be served under an umbrella.

As for the town, Punta lies 70 miles east of Uruguay's capital, Montevideo, and is about the size of Annapolis. The bustling main drag, a mile or so long, is Avenida Gorlero.

Lined with medium high-rises, Gorlero is busy all day in season, but roars to pulsating life after midnight, when Uruguayans finish their supper and head out for late-night socializing. Discos blare, traffic is heavy, alfresco coffee shops are full. About midway down the strip is a public park where artisans sell their wares under a big tent. At a little outdoor stage there, I watched clowns entertaining preschool kids with songs and games at 1 a.m., night after night. It was charming, once you got over the weirdness of the hour.

Punta seems utterly and completely safe. "Many people come here because they can wear their Rolex watches and gold chains in the street without worrying," said Andres Camacho, a travel agent. "You can't do that in Buenos Aires or Rio."

Indeed, my bicycle man looked puzzled when I asked about a lock. He said I could leave the vehicle on the street all night without a worry.

One of Punta's curious wonders is its old cars and motorcycles, some dating from the 1930s, when the nation changed from right-hand drive to left-hand. You see old right-hand Chevys and Fords, as well as British Morrisses and the like, in various states of disrepair and rusty ruin, still puttering along.

Motorcycles are also attention-grabbers. There must be at least a dozen old English, single-cylinder, 500 cc Matchlesses in Punta, all of which start with a thunderous roar that would wake the dead. Also, there are 1950s-vintage Harley-Davidsons, Triumphs and even one rare old British Ariel, which I helped the owner bump-start one misty morning.

Many of these handsome relics are in excellent shape and have for-sale signs on them. A fellow told me you can buy an antique British bike in good shape in Punta for as little as $500, but every time I tried to talk price with a bike owner, I got lost in the miasma of Uruguayan currency.

They have "new pesos" now, of which it takes about a million to do anything. Well, not really, but you do find yourself negotiating in the thousands over a simple sandwich. The exchange rate seems to go up daily (the dollar gaining!); when I left, it was 915 pesos for $1 (it's now closer to 1,242 pesos for $1).

It helps to have a little Spanish in Punta, since many Uruguayans simply don't do English at all. The younger the Uruguayan, it seems, the more likely he is to have some working English.

But who needs language, anyway, when you can simply smile, say "Hola!" and be rewarded with big, wet kisses?

For more information, contact the Uruguayan Tourist Office, 541 Lexington Ave., Suite 356, New York, N.Y. 10022, 212-755-1200, ext. 346.