Fifa 11 is not the most recent addition to the title, but a lot of people like it the most because it was the point before defending became a lot more complex.
Anyway, at $3.87, if you haven't played a Fifa game before, I highly recommend you try this one out - it's such an awesome game.
This store seems to be legit - check out their Facebook page:
https://www.facebook.com/OnlineKeyStore
It was the point before defending became far more realistic and less like homing missles, plus you can always turn that feature off if you're playing offline!