patio11 is right, you're about to have a major problem with gift cards going bad, which were bought with stolen credit cards. Happy to give more advice, you can reach me via my HN profile. Source: In a similar business for 16 months. (We sell gift cards for $ or BTC, but don't buy gift cards with bitcoin)
How do you handle compliance for your business (the bitcoin->giftcard one). From this discussion it seems like a total minefield. Do you ask your customers for their ID Proof/Address Proof ? (KYC/AML style) I know fraud isn't an issue for you at all because the bitcoin payments would be irreversible.
I took a look through your site and there are some really great deals (7% cheaper! wow!), great work btw!