"I mean, it was really that quick. [It] went from an absolute seller's market where you could sell a property literally in 24 hours to a buyer's market where it can take three, four months to sell a property," Celnicker said.
Celnicker attributes the chill to higher interest rates and a punishing Florida hurricane season. But he and his investment partners had put some money aside, rented out all their properties, and weathered what they hope is the worst of it.
"I knew as long as I could ride out those first couple of months, then I'd be safe," Celnicker said.
There are a lot of unknowns today in south Florida real estate, where there's concern that words like "hot" and "flip" may soon be replaced with "chilly" and "stalled."
One reason: Experts now say Miami Beach has perhaps the most overvalued real estate in America.
"Construction costs have gone up, prices have gone up and so there is a point, we think, that buyers are reluctant to overpay for an apartment -- especially when there's an oversupply," said Zilbert.
He remembers the moment he realized the market was changing.
"There was a day that I woke up at the launch of a new building, and I contacted my clients and I sent out my e-mails and I did my advertising, and not a single person wanted it. Not a single person showed up. And the feedback was, 'I think prices are gettin' outta control,'" Zilbert said.
But even in harder real estate times, Zilbert has a way to make money and, he said. He can bail out investors who may have gotten in too deep. His Web site, CondoFlip.com, can connect desperate sellers with "vultures," people who are ready to buy at a low price.
And he's recently added something called the panic button.
"The CondoFlip panic button gives the seller an option -- push the panic button and then we have vultures lined up, and it's something that is going to probably happen more often than we would like to see. And people will lose some money," said Zilbert.
Celnicker agrees that desperation has hit the south Florida real estate market. "I think there's going to be a lot of desperate sellers," he said.
And speculative investors who bought into the high-priced, preconstruction condo market in south Florida may be in for a rough ride, Celnicker believes. But he won't be one of them because he bought low-end properties that can be rented to cover costs if there's a downturn in the real estate market.
"This is not a 'get rich quick' thing. This is a minimum two- to three-year investment. Real estate is a long-term investment vehicle, and you have to be prepared for contingencies. And if you are, then I think it's a very safe investment. But if you're just jumping in because your neighbor made $50,000, you could get stung," Celnicker said.
Buyers, Zilbert says, are becoming more cautious. "There's not a day that goes by that I don't take a buyer to a property he or she will find something he absolutely adores, wants to purchase it, but at the end of every conversation is, 'I think I'm going to wait six months and see what happens.'"
Some realtors say even if the "flipping" frenzy has cooled for some investment speculators, Florida's got an ace in the hole. It's still a place where people want to buy homes and condos they actually plan to live in.
"We have a thousand people moving to Florida every single day. Then add to that all the vacation, the second-home buyers from Europe and around the world," Zilbert said.
If you're ready to buy a south Florida residence right now, the market could be working in your favor.
Take those Delray Beach condos launched last summer. It turns out 40 percent of those units are still available, and some of the prices have dropped dramatically.
That's good news for new buyers, but not so good for those who paid $100,000 more just eight months ago.
But, after all, no one ever said buying real estate came without risks.