I for example purchased some jewelry that was about $200 after a steep discount, but i first purchased a $100 E-Gift Card with one AMEX card and got back $15, and then purchased another $100 E-Gift Card with another AMEX that had the offer saved, and got another $15 back.
(However it took over night (and they called me to confirm the email) to receive them). I then used both Gift Cards to complete my purchase.