Maybe some clarification is needed. Are you looking for homes that have already been foreclosed on by the lender (the classic definition of a bank-owned home), or are you looking for homes being auctioned off by the lender under a trustee's sale? The former are almost always listed and sold through real estate brokers. Sometimes they will be sold after foreclosure through an online or real time auction, usually through http://www.auction.com,
but even then most of those are listed with a broker and publicized on the MLS. Any agent can show you those homes if they are members of the local MLS. Pick a knowledgeable and experienced agent to work with if you aren't doing so already. They can help guide you through the complexities of the process and save you tons of money and heartache.
Trustee's sale auctions are different. Those are homes being sold out from under the owner on behalf of the lender, which is literally the foreclosure action. Those are sold for cash only in the form of cashier's checks, you have no ability to preview the home, and the sale is "as is, where is". You assume all liability for your purchase and have no investigation or contingency rights. If you have a high tolerance for risk and lots of cash available, this may be what you are looking for. It is a highly competitive setting, and most of the buyers are experienced investors often part of investor groups.
Many of the homes auctioned here go back to the lender because the opening bid is higher than the savvy buyers competing there are willing to pay. Those homes taken back will become the REO, or bank-owned listings mentioned above.
Hope this helps. Please feel free to call me if you have more specific questions about local real estate.