While I'm not completely opposed to the idea, it'd have to be properly implemented.
There'd have to be some kind of "Galnet Auction" option, which was available at every station.
People could submit stuff (ships and modules) for auction at any station and then there'd be an auction held at a set time every week and, again, you'd be able to bid from any station, anywhere.
It'd have to work like that to prevent it being used for "gold trading".
If it wasn't a "universal" thing, you could offer to pay me, say, $20 for a Cr1bn Corvette, we could meet at some obscure station and then I'd put it up for "auction" for, say, Cr100 and you could buy it.
By making the auctions "universal" it'd mean every item would go for whatever it was worth in in-game credits and nobody'd be able to flog stuff for real currency.
TBH, the new engineering system has pretty-much killed the need for auctions because now there aren't any "super-rare" mod's that people might be willing to pay silly money for.
Auctions are usually used when someone has an item(s) that they can't sell at market or wholesale prices; and there is no dynamic "player" market in-game so one would have to be built.
Well, considering you get most of your credits back for selling a ship and modules, I don't see how ship auctions would add anything. Then add the discounts for ships and modules from several or more sources/locations, auctions would be useless because no one would like to sell a ship for less than what they can resell it for (unless for a friend/charity).
Also ship skins would need to be purchased along with any auction. So you'd have in-game credits and RL monies to fork out; unless you're asking for a credit-to-cash/cash-to-credit currency conversion during payment.