Thanks for the alert!
Since this subject is getting refreshed, I can also confirm the earlier recommendations for GiftcardMart.com. I gave them a try, and have since been selling almost exclusively to them in the past 1.5 yrs. They have recently went "boutique", and now buy exclusively from their "volume partners". This does not really obligate the sellers to any volume of business. It only requires that new sellers go through a vetting process (more like getting acquainted). On the sell side, they started coding their transactions as office products -- so Chase INK and AmEx SimplyCash users can get 5X while buying GC's.