Mortgage down payment requirements are considerably stiffer than for primary residences, and lenders are scrutinizing income more closely, which can make financing especially difficult for the self-employed.

The tougher terms make for a “bittersweet situation” in the Hamptons, said Judi Desiderio, the president of Town and Country Real Estate in East Hampton.

Many of her clients “have given up on getting mortgages — totally,” and instead are paying cash, she said. But as much as she hates to say it, Ms. Desiderio said the real estate market is probably better off this way. “If money was as easy to get as before the crash,” she said, “I think we would have real estate pandemonium. It would create a whole new bubble.”