+1 with has been posted.
REOs of partially completed houses are going cheap right now as long as you have the knowledge, money source and patience these can be a real good way to go. A lot of the building permits have expired so this may take some time. Plan accordingly.
Check with the auction company to see if they have a title commitment you can read or have a copy of to see what is recorded against the property.
If the house is being foreclosed on, then you must show up with the funds at the trustee's sale, which is typically at the county courthouse but not necessarily. One easy payment.
If the house is being sold by an auction company and is not a foreclosure, you may be able to close on the purchase, post auction, but I'd get the funds lined up before hand as sometimes the closing is short on thses types of auctions so you don't have time to shop for financing.
If it's a foreclosure auction, the trustee will tell you what the opening bid is. If it's a private auction, there probably is a minimum bid amount the seller will accept. Either way, call the people having the sale and they'll tell you.