A great local agent can provide this for you. Repossessed homes, also known as REO's (real estate owned) are typically listed by a local agent and can be found on most search sites. Pre-foreclosures that are heading toward auction, are not listed for sale and require cash, have no preview period, don't allow inspections or allow any type of contingency. These homes are either snapped up by investors who have years of experience or get no acceptable bids and eventually become REO's.
One last thing, not all foreclosures are good deals. Some are money pits, some are in need of moderate repairs and others require major. In the worst case, some need to be demolished. Buying at an auction for anyone but the most experienced buyer/investor is real estate speculation. Be very cautious if you go down this track and get all the professional guidance you can.