Some car auctions are for dealers only. I'm not sure if this is ever the case for gov't auctions. I've been to gov't auctions in the past though, and it works like any other auction: you're purchasing the vehicle as-is. (I'm not sure about manufacturers warranties that may still be in effect though) I haven't purchased a car through a gov't auction though, but watched as several people I know have purchased trucks, cars, etc. All were surplus items.
Also, no one should be paying some company to let you know when the "secret" auctions are.... The auctions are not a secret. (Ditto all the sites that will sell you a list of repo'ed homes... that's public information that can be gathered with very little effort.