Go to HUD.gov and click on your state's page. That'll get you a lot of the truly bargain-basement foreclosure listings because it covers foreclosures with FHA-insured loans. Your county web site may also have lists of tax sales, though those are more complicated by a long redemption period. Auction.com and WilliamsAuction.com have foreclosure listing as well, but keep in mind if you decide to make an offer that the auctions have reserve prices that in some cases far exceed the appropriate price of the home.
Also, you can just look at the MLS for your state, narrow it down by area and price range, and look for those where the ownership field or notes list "bank owned". Listingbook.com offers an easy MLS search interface, though I think you do have to register (free).
We've bought two foreclosures and never paid for access to listings. All those companies are doing is offering a more convenient way to access information that is already public record, all in one place rather than having to look at various sources, and to me that isn't worth paying for.
