EAST BERLIN, JULY 2 -- A wave of East German shoppers today wandered through new and restocked stores with hard cash but displayed remarkable caution at the cash register.

At bright, new electronics shops and remodeled department stores, wary customers peppered salesmen with questions and compared prices. Shoppers waited in long lines to get into supermarkets where Western goods jammed shelves that only days before had been stocked with a limited selection of East Bloc products.

Their reluctance to buy followed warnings from authorities to avoid a spending spree that could sent inflation soaring.

The two nations' monetary and economic systems were joined Sunday under the terms of a May 18 treaty that scraps the centrally controlled economy imposed on East Germany when the communists took power after World War II and creates a single free-market economy controlled by West Germany. East Germany's communist government was peacefully overthrown last year and elections for a new united German government could be held before the end of the year.

In the days leading up to Sunday's union, West German companies quickly established a presence in the East, with many selling their goods to East German stores and some opening branch outlets on the other side of what was once the Iron Curtain.

Exhibiting the caution and discipline that Germans often have shown in the face of change and uncertainty, East Germans have turned in only a portion of the East German marks they are entitled to exchange for West German marks at the preferential 1-to-1 rate, preferring instead to keep most of their funds in bank and savings accounts. Moderate withdrawals from accounts by East Germans have averaged only about 800 marks ($485), far below the limit of 2,000 marks ($1,200) set under the rules.

This has kept the amount of new money in circulation well below expected highs. That fact, together with the reluctance East Germans showed today to spend their new German marks, helped maintain the strength of the currency on world exchanges today and gave the German stock index a boost to 1,912.58 from Friday's close of 1,879,90.

Their careful steps at the outset of economic union suggest that East Germans, while hailing Sunday's decisive step toward full German reunification, recognize that difficult times lie ahead as their collapsed economy is swallowed up by prosperous West Germany.

Unemployment already has shot in the past six months from almost nothing to more than 130,000. Some specialists predict it could hit 20 percent of East Germany's 9 million workers by this time next year as inefficient state-run enterprises are closed or sold off.

Prime Minister Lothar de Maiziere said in an interview published today that the gap between rich and poor in East Germany is likely to widen significantly, at least at the outset of economic unification. Echoing his countrymen in the streets, however, he expressed satisfaction that individual achievement will be rewarded under the new free-enterprise system.

{Union officials said about 30,000 workers in 10 factories around Berlin staged brief warning strikes or protests Monday, the Associated Press reported. Strikers demanded higher pay and better working conditions, East Germany's ADN news agency said.

{East Berlin's 66 coal dealers used their trucks to block loading points in four locations around the city, protesting abandonment of state subsidies.}

While some East Germans hauled boxes of new purchases out of glitzy stores that had appeared in empty storefronts over the weekend, others wondered what the massive infusion of Western goods will mean to their own jobs.

"With all these {Western} products, we're destroying our own economy," said Annette Makulla, an engineer who waited 20 minutes to get into her neighborhood's state-owned supermarket.

"We're taking jobs from our own people," Makulla said. "Okay, maybe our detergent doesn't smell as good or it isn't friendly to the environment, but I've got a budget to keep."

That sentiment was rare on East Berlin's central Alexanderplatz, where West German merchants hawked goods ranging from gold chains to sausages, on tables and from the back of trucks.

Helmut Thruen and his son, Jorg, carried a new 20-inch Blaupunkt color television across the square.

It cost Thruen, a railroad dispatcher, 698 of the 2,000 German marks (about $1,250) that he exchanged for his now-useless East German marks on Sunday. His previous TV set, an East German black-and-white set he bought six years ago, cost him 2,600 marks. That time, he had no choice of model and had to wait many months to get a set. This time, he visited four stores in one hour, compared four models ranging in price from 698 to 1,200 marks and bought the cheapest one.

"It's a surprise birthday gift for my wife," he said. "Now I'm getting a vacuum cleaner, and then we'll see."

"It's so exciting, the kids are running around the market to see everything new," said Gurdana Samtleben, an East Berlin shopper who stared at two brands of milk -- one West German, the other East German -- and then chose the Western one even though it was more expensive. "To be honest, our milk tasted good too. But things change."

Horst Bloek, 62, an economist who spent the morning shopping for an electric razor, marveled at the idea that a salesman would spend 20 minutes explaining the intricacies of the appliance to someone who might not make a purchase.

"For us, a conversation with a salesman is very unusual," Bloek said. "Until now, you would stand in line and when you stood in line, that meant you wanted what was at the end of the line and the salesman didn't have to do anything."

But fears of losing the extensive social protection provided by East Germany's former communist government produced a cautious attitude among many East Germans. Martin Wiele, a West German sausage seller who has been setting up his van full of wurst in East Berlin for several weeks, said business slowed dramatically today. "They're afraid of what's going to happen now, so they only buy small things," he said.

Now that the treaty for economic union has gone into effect, de Maiziere's government was reported ready to begin negotiations on a treaty covering political union. The discussions with the Bonn government are likely to be the final significant task of the coalition government that emerged from East Germany's March elections.

Before political union can be completed East Germany must organize regional elections to reestablish states along the lines of the five that existed before the communists took power after World War II. The voting, scheduled tentatively for September, would open the way for East German state governments to join the West German federation under a procedure provided for in West Germany's constitution.

With the two Germanys merging at a rapid pace, only forging international agreement on the unified nation's place on the European strategic map remains a major hurdle. The Soviet Union, which still has about 360,000 troops stationed in East Germany, has objected to the prospect of a united Germany remaining in the U.S.-led NATO.