It was reported on Flyertalk that some Costco locations have begun selling American Airlines gift certificates at a 10% discount ($269.99 for a $300 certificate). So far, people have only confirmed seeing them in a handful of stores, but my gut tells me if some stores have them, others may start carrying them soon (or people just haven’t found them yet in other stores).
I’m not advocating a rush to Costco, but on your next visit, if you could confirm whether they have them and comment below, that would be great. 10% off airfare is a great deal, considering fares have been skyrocketing recently. Every dollar saved counts!