The massive collapse of the hurricane insurance market for Florida businesses has morphed from an economic headache just weeks ago into a clear and growing threat to the region's economic vitality, experts say.

Among the troubling signs:

• Some sales of commercial property are grinding to a halt.

• Business borrowers are bordering on default with their bankers.

• Companies are developing plans to create their new jobs elsewhere or move out altogether rather than pay the high cost of operating here.

Ultimately, business leaders say, the lack of affordable windstorm insurance could do something no hurricane ever has done to South Florida: produce permanent, crippling economic damage.

''It is a crisis situation,'' said Frank Nero, head of the Beacon Council, Miami-Dade's tax-funded economic development agency. ``This is not just a case of companies making less money. It's not being able to stay here, or expand here, or move here. And that ultimately translates to fewer job opportunities.''

It isn't just a headache for business owners -- much of their higher costs are likely to ripple into consumers' pockets.

For instance, Michael Lefkowitz, who owns three Dunkin' Donuts shops in South Florida, had to raise prices when electricity costs soared earlier this year. Now his insurance is going up 60 percent, leaving him with two unappetizing prospects: raise prices again and risk alienating customers or absorb expenses that weren't built into his budget.

''I'll have to see what the market will bear,'' Lefkowitz said of price hikes. ``I may turn away customers who don't want to pay 15 to 20 percent more for a cup of coffee or a doughnut.''

Lefkowitz says the pain is going to get worse, because his landlords are also passing along higher insurance costs.

That represents the next phase of the situation, said William Holly, president of Holly Real Estate in Miami. The increases hitting building owners ''won't be felt by tenants until next year because pass-throughs are typically calculated at the beginning of the new year,'' Holly said.

Unlike homeowners, who can turn to the state-run Citizens Property Insurance, businesses have no Tallahassee-backed windstorm insurer.

Alarmed civic leaders are banding together to beseech Tallahassee and even Washington for relief. The Broward Alliance, for example, is polling its members on their specific problems in order to form a battle plan.

''Is it access? Is it cost?'' said Jim Tarlton, the Broward Alliance executive director.

Actually, at the moment it's both -- and more. Some insurers are leaving the state, others are hoisting premiums and some are pushing deductibles to levels that could themselves prove devastating if a business gets damaged.

And many business owners worry time is short, the efforts are fledgling -- as the most active period of the hurricane season looms.

Secure Wrap founder Radames Villalon is an example. The Miami firm, which provides baggage-wrapping services at airports, saw windstorm deductibles rise from $61,000 last year to a whopping $1.5 million this year.

''I already told them, I'm not going to take this policy,'' Villalon said.

LENDERS' DEMAND

But that, in turn, could put him into hot water with his bank, which requires adequate insurance on his mortgage and line of credit.

''I called the bank and told them they have to do something,'' Villalon said. But he is growing weary of dealing with it, and notes there's no compelling reason why he must remain in an increasingly costly South Florida.