The two auctions you listed aren't legitimate. Both buyers had zero feedback and now they are NARU-ed.
Just looking at the first page of completed auctions, almost every auction seems to have a buyer or seller who's either zero feedback or NARU'ed.
I was able to pick up 2 extra Forza guides (still wrapped) and one extra Doom 3 for Xbox (not wrapped). I'd be willing to trade them for just about any newer Xbox game guide, just send me a PM.