Who gets the money from the sales of these items?
If they are bona fide government surplus auctions, the government. Keep in mind that the government hires private auction-houses to do this for them. Once they have been properly sold and are legitimately in private hands, they can be resold just like any other private property. I can buy the MOCR control console from this auction house, and then turn around and sell it again on eBay just as with any other equipment.
For government property that was simply discarded in the normal course of business, or formally decomissioned or abandoned (paperwork is required), the person who reclaimed it from refuse is generally its legitimate owner.
For government property that just walked out the door with some lucky employee, the sale of it raises all kinds of legal issues. I suppose it would matter whether it had historical significance and great enough monetary value to attract attention.