I don't think you need to buy a giftcard online at a discount. To me it sounds like you get the $10 off your first reload of $100 and once per AMEX card. I have three Amex cards and plan to buy three $5 gift cards at my local WFM. I'll then set up one Amex on each card to autoreload for $100. Thus when I deplete the $5 it will reload $100 and I'll either receive $110 on the card or only be charged $90 and get $100 on the card. No need to do TCB or plastic jungle etc to get the $10.