I went back and got a different employee to ring me up. Surprise, the coupon worked this time (the other guy was an obvious moron). I got the 4th gen 16gb for $278 as well, nice deal.
I went to my local Gamestop to get an ipad 4 with the 25% off coupon. The coupon didn't work, the clerk said it was because the ipad was already on sale for 10% off and you can't combine two promotions... Not sure if he even knew what he was talking about.