They reduce the price by about 10% every thirty days, as far as I can tell. They don't last that long here, and most of them in my area go for full price or over. Check the website, and they are generally updated every Friday. Preforeclosure is just that - Pre, meaning it hasn't gone to sheriff sale yet. You would have to check the courthouse records for lis pendens filings and try to get the owner to sell to you directly. However, many of these owe more than the home is worth, whereas the REO and HUD listings are selling at appraised value, rather than the mortgage amount. Find an agent in your area that deals in foreclosures.
_________________________
Comments made are my opinion, and not intended to be legal advice of any kind.