MIAMI - The champagne-popping days are over for Natalie and David Luongo, who banked enough money flipping a South Florida condo three years ago to stage a $100,000 wedding.

Now the couple are spending restless nights wrestling with the question that looms like a guillotine: Should they walk away from the $117,000 deposit they plunked down on another investment condo in the ritzy Miami-Dade enclave of Bal Harbour?

Or should they close on the one-bedroom unit, which is similar to others now on the market for less than the $585,000 they agreed to pay?

"It's painful and scary," Natalie Luongo, 31, said. "We saw the frenzy, and we bought in. Now we're paying the consequences."

Just how many other speculators face the same dilemma in the nation's most glutted condo market will become clear during the next two years. That is when 25,000 new condo units, most of them rising in or near Miami's downtown, will flood an area already saturated with 23,000 condos listed for sale. An additional 40,000 units have been approved, but analysts doubt the majority will break ground. (See map with condo locations.)

Orlando and other Florida cities -- Naples, Fort Myers, Tampa and Sarasota among them -- also have huge condo gluts. With 4,440 condos listed for sale, Orlando has an unprecedented 29-month supply, and last month sales plummeted 64 percent lower than a year ago.

But Miami, with its unmatched volume and untold number of speculative buyers, is ripe for the hardest fall in the U.S.

"Miami is the poster child for the condo bust," said Jack McCabe, CEO of McCabe Research & Consulting, a real-estate market-analysis firm located in Deerfield Beach. "There are probably only two cities in the world with more construction: Shanghai and Dubai. Unfortunately, there is going to be a lot of foreclosures . . ., and developers, lenders, title companies and real-estate companies will go under."

Many analysts, McCabe among them, predict the area's condo collapse will drag the rest of the state into recession. Other experts scoff at that notion. But nearly all agree grim times lie ahead.

Usually joyous milestones, closings in Miami are about to become somber days of reckoning for electricians, waiters, retirees and other amateur speculators who counted on making a quick killing in a market they thought would rise forever.

No one knows how many units speculators bought. But as early as 2004, McCabe and Lew Goodkin of Miami-based Goodkin Consulting warned that up to 70 percent of the condos rising in Miami were being snapped up by people who didn't plan to hold on to them, much less live in them.

That was evident from the hordes who camped overnight, fought over lottery numbers, even paid homeless men $20 and a pack of cigarettes to hold their places in long lines, all for the chance to put 20 percent deposits on condos that existed only in brochures. The frenzy for some projects was so fevered that some developers raised their prices hourly.

"It was a nightmare. Lines around the corner. People screaming into phones. I would look at them, and think, 'You don't know what you're doing,' " said Mark Zilbert, president of Zilbert Realty Group.

Many told a similar story: They had a friend who made $100,000 flipping a new condo, and they planned to ride the same wave of escalating prices. All they had to do was put down $60,000 on a $300,000 pre-construction unit and resell it when the value climbed to $400,000 -- before the building opened, and before closing and mortgage payments, maintenance fees, insurance and taxes kicked in.

That meant anyone could risk $60,000 and pocket $100,000 without actually buying anything.

Some investors were experienced players like Barry Beschel of Aventura. After the dot-com stock-market crash in 2000, he said he had no trouble persuading his buddies to park their money in Miami's sizzling condo market.

"All my guys in New York were like, 'Yeah, flipping condos in Miami.' It was a sexy commodity, and it was fun to make money," Beschel said.

It was also easy. Beschel, 50, said his group followed well-known developers such as The Related Group's Jorge Perez to their next project. The king of Florida's condo market, Perez has built or manages more than 55,000 units in the state and is building at least nine new towers in Miami as well as a 441-unit, luxury condo hotel in Celebration.

From 2001 to 2005, Beschel said his group bought about 50 pre-construction condos, sometimes 10 or 12 at a time. They would pay about $300 a square foot and, once the building sold out, return the condos to the developer, who would resell them at $350 a square foot. The difference between the original contract price and the new one -- $100,000 on a 2,000-square-foot unit -- would go to Beschel's group, minus a commission.

"The developer would take his commission, and we'd take our profit and everybody was happy. When the market was cranking, it was a brilliant business model," Beschel said.

But beginning in 2006, Goodkin said, it became clear the market was saturated. Speculators, at least the wise ones, had fled. Buyers stopped walking through the sales-office door. Some developers halted resale programs to concentrate on their own inventory.

And whoever held a contract was stuck -- with prices at their peak. Now, foreclosure filings are up by 30 percent in greater Miami over last year.

For Beschel, whose group still holds contracts on two condos with falling values and looming closing dates, financial ruin isn't a worry. He figures his group made "a few million dollars," so walking away from two $100,000 deposits is no big deal.

But for untold others, such as the Luongos, losses could be devastating. Owners of a gourmet shop, the transplanted New Yorkers poured their life savings into deposits on four condos they had planned to flip for a quick profit.

The plan worked for a one-bedroom condo conversion at The Residence in Hollywood. They agreed to buy it in 2004 for $207,000 and sold it before closing for $330,000.

But they were forced to close on a condo in Boynton Beach, where they now live, and they face the prospect of losing nearly $200,000 they put down on two condo conversions at the Harbour House in north Miami-Dade County. One is a $350,900 studio, which Natalie Luongo said is smaller and in a different location than the one she agreed to buy in December 2005. It is the subject of litigation.

The other is a $585,000 one-bedroom unit similar to others now available for about 25 percent less. As the September closing looms, the Luongos are distraught. If they can't secure another mortgage, the decision will be made for them. They will have to walk away from their $117,000 deposit.

But if they secure financing, they know they will be stuck with a property that could be as difficult to rent as it is to sell.

Gregg and Mary Mullins, 70-year-old retirees living near Fort Myers, learned that the hard way.

Last month, they finally rented out the two-story $885,500 penthouse they closed on last year in Blue, a concave tower overlooking Biscayne Bay. But the $2,800-a-month rent they're collecting is less than half their monthly mortgage payment, maintenance fees and property taxes. Yet, as Mary Mullins said, something is better than nothing.

The couple never planned to live in the condo, but jumped at buying it at pre-construction prices in 2004 after friends shared a familiar story.

"They said they made lots of money, so they told us to try it and maybe we could make lots of money, too," Mary Mullins said. "But that didn't happen. We don't know what happened."

A sheepish Tom Leon says he knows. The retired businessman from Illinois said he knew he had made a mistake about six months after he put down $200,000 on two $500,000 condos at the end of 2004.

"Every 2 inches, I'd see another [construction] crane, and I knew: There is no market that can absorb these many units," said Leon, 72. "It doesn't take a rocket scientist to say, 'Gee, who's going to live in all these buildings?' "