HDTV: Want a great deal? Move fast.

Flat-screen television sets were expected to fall during the hoiday season and, sure enough, early Black Friday sales are setting the pace. But you have to move fast to get the best deals.

This past weekend, Walmart began offering a 32-inch Vizio HDTV with 720p resolution for $298. But Best Buy and Amazon had an even better deal: 32-inch HDTVs for $259.

Amazon.com, for example, was selling TCL's 32-inch L32HDF11TA model with the same 720p resoluion as Walmart's Vizio for $259, according to I4U News, a technology lifestyle magazine and shopping guide. But as of Tuesday morning, the price had jumped back up to $299 with free shipping.

Best Buy had been selling three models of a Dynex 32-inch HDTV for $259, the website said. Those prices, too, have jumped back up to $299.

The Black Friday sales happen so rapidly that it's tough to make an informed decision. One trick, recommended by Black Friday sales watchdogs, is to look for the retailer's return policy. If it has a 30-day free return policy, you can buy today's deal and see if a better one crops up.