The buyers will state they paid more than they actually paid, to be able to file a lower gain later.
The marshals will say it was lower than the actual price, the difference entered into a slush fund to use for random gifts to friends. Selectively, they might report a few customers to the irs.
Not much of a conspiracy theorist, but i can't imagine that that information would not be released. In fact i can't believe no one has did the research on this to see weather US Marshals released the prices before on mansion and such even with freedome of info requests?!?

Just too lazy to research this myself
I'm not a conspiracy theorist either but I'm also not a conspiracy denier.
I can't believe that the US Marshals aren't obliged to report the amount of revenues from the liquidation of seized assets. I also can't believe that the American public would stand for non-disclosure, but I'm a Canadian and it's not my position to comment another country's domestic policy so I'll leave it at that.
I will say however that historically, this sort of thing tends to be leaked if it isn't released voluntarily. My guess is we'll all know before long.