If you're in a lien theory state then the auction is held not by the lender or an auction house but by the public trustee. In these states the borrower retains title to the property when they purchase and the mortgage is simply a lien filed by the bank on the property. The public trustee holds all of these records.
When the borrower defaults the lender notifies the public trustee and the foreclosure process is started. When this happens the information becomes public on the Public Trustee's website.
Here in Colorado finding foreclosures is quite simple. Every property in some stage of the process is searchable. Investors simply monitor the properties as the auction date draws closer and then about 2 weeks before the auction date they begin their due diligence in earnest. 24 hours before the auction the Public Trustee creates a finalized list and publishes it on their site with what the opening big will be . This number is generally what the loan payoff amount is.
In my county you simply fill out a form with the Public Trustee with some basic personal information, and if you win the property at auction payment is due in full by the close of business that day or the winner will be the next highest bidder.
So before you pay for a subscription to a website make sure the information isn't available via that counties Public Trustee website.