Home prices are changing a lot right now, and you can't make a smart bid if you don't know exactly what's going on where you want to buy.

For the first time since the mortgage crisis struck in early 2007, prices are falling in most American cities.

The National Association of Realtors' latest report shows that the median sales price in 77 of 150 markets was lower during the final three months of 2007 than the last quarter of 2006.

That's a significant increase from the 51 markets that posted declines in the third quarter of 2007.

And where things are bad, they are very, very bad.

More than a dozen cities, including Los Angeles, Tampa and Sacramento, saw prices drop more than 10%.

Before you buy, know how the median sales price in your town has changed over the last year.

Be aware that the outlook for this year is not good. Most economists expect property values will continue to fall.

Let our full report on home prices keep you up-to-date on the latest trends.