Originally Posted by
Gondorian
Almost all non-foil cards might as well be sold now.
As far as I know, when the Auction House starts up, the Merchant will pretty much only have stock bought from other players (instead of restocking himself as he does now), and his prices will be linked to the auction prices. This could mean some cards drop hugely in value (e.g. Drain Power) because he has such a surplus of them and no one wants them. On the flip-side, some cards could increase in value due to the demand, but this is where the Merchant exception will kick in - if a given card's price goes "too high" (where "too high" is determined at Wulven's discretion) then the Merchant will manufacture copies himself so as not to lead to insanely huge prices for the most in-demand cards (which would cause hoarding and pay-2-win issues).
For the foils, you will either have to wait for the auction house or just sell for double value of a non-foil to the Merchant if you really want to sell it. Likely each foil will be worth more than this when auction house launches, but it is there as an option in case someone who finds a foil in a booster pack would prefer the gold right now (e.g. building their non-foil collection).