What's driving home prices down?

From Marketplace by Stacey Vanek-Smith: The median home price is down about 17 percent from last year. The reason? Foreclosures, of course. Buyers are bargain hunting. And owners of more expensive houses aren't selling unless they have to. But there's another problem says economist Lawrence Yun with the National Association of Realtors. He says appraisals are coming in low. If the appraiser values the home at less than what the buyer agreed to pay, the buyer, not the mortgage lender, has to make up the difference...