As the U.S. housing market cools from last year’s overheated state, sales of homes at the top haven't been following the same script. Prices and sales at the upper reaches are soaring.

Sales of homes in Southern California costing $2 million and more are at record levels. Sales of homes costing more than $10 million in Los Angeles are up almost 400 percent since 2007. In Miami, luxury home sales are roughly double 2007 totals.

But the rise in high-end sales isn't just a cash phenomenon. Low mortgage rates are crucial because the well-off tend to have good credit records and can secure loan approval.

Although New York's high-end real estate prices have been setting records too, their sales haven’t jumped as in other markets largely because the 2007 volume and prices were already so high as a result of record Wall Street bonuses.