Capcom Store. Why? Because everything is currently 10% off retail.
Admittedly, you'll have to do some work to get the 10% off, but the process is as easy as: 1) Add an item to your cart. 2) Exit the shopping cart screen by clicking towards the storefront. 3) A pop-up appears with a 10% off offer. Just make sure your pop-up blocker is turned off.
Once the coupon code is applied, you can grab any flavor of the new SFIV FightPads or even a too-cool T-Shirt. Sadly, the highly coveted FightSticks are sold out. Note too that you'll also have to account for shipping charges.
[Via Cheap Ass Gamer]