On my server, aces for the Darkmoon Faire decks tend to sell on the auction house for between 150 and 200 gold. That is, except for the ace of warlords, which seems to have bottomed out at 4 gold or so - and there tend to be ten of them on the auction house at any given time. The drop rate of the ace isn't high enough to make getting these quantities easily, which does make one wonder where they're coming from. The usual answer - farmers with teleport hacks, which allow them to jump directly to King Gordok in Dire Maul, kill him, and collect their loot. This video, which recently showed up on Google Video, shows us what might actually be happening here.