Right now, as far as I can tell, deckbox only shows me a list of people selling cards that are on my wishlist. That's not to say I don't enjoy window shopping from time to time. I might not have it on my wishlist, but, as an example, if I see someone selling a Berserk for $35 I might pick one up.

Not yet, but we're cooking something up. Specific cards you can see on the card page who's selling. (Sadly Berserk seems to not have any sellers yet).