volumebuy.com is offering AA certificates at discounted prices right now (~15% off). They have $50, $100, and $250 certs. The higher priced certs are at a fixed 15% off (if you can wait two weeks). The cool part is that as more people buy $50 certs the price drops. Right now they're at $43.75 but could go as low as $37.50 (25% off!). This particular deal ends at 1pm today but may be back.

$50 certs: http://www.volumebuy.com/ then click on the Volume $$$ tab.