You need to start with 3rd Party.
You can trust Market2Market, AssetValuation, Summit Valuations, Clear Capital.
Truth is, most Asset Manager's out source the majority of the bpo's to these 3rd parties. I typically get 30+ REO listings a month and did 1 dby last month for a non listing.
You have to start somewhere. Everyone has this perception of riches in REO. Trust me when i tell you, you will lose more upfront than you make.