These will give you the links to the Bank/Gov sites.... http://www.mortgagenewsdaily.com/wiki/REO_Database_List.asp .... http://www.biggerpockets.com/bank-reo.html
You will find this type of info.... http://reosearch.fanniemae.com/reosearch/ ... http://hud2.towerauction.net/CA.htm ... http://www.pasreo.com/pasreo/public/propertySearch.do
If it Tax Sales you are interested in then try this.... http://www.sco.ca.gov/ardtax_public_auction.html
For your county.... http://sdtreastax.com/pts_currentyear.html ... http://www.bid4assets.com/storefront/index.cfm?sfID=474 .... This search tool may be of use to you.... http://publicrecords.onlinesearches.com/Foreclosures-and-Tax
Auctions are a "You must have a Due Diligence approach" but you can look.....
Good hunting, Dunes
Your question is nowhere near specific enough to answer. There are foreclosed out there from $20,000 to $3 million and even higher. It depends on what specific area you are asking about. Contact a local real estate agent to get the most accurate info. Good luck.