Originally Posted by Ben Carufel

Programming a key is a 30 second job (at least in the E39, I'd expect it's very similar in the E53) that takes only a few button presses while sitting inside the car.

I believe it's also referred to as "EWS Pairing".

To the original poster; I would find a cheaper dealer. Keys are generally not something you can do mailorder, as all dealers should ask for proof of ownership and photo ID before letting you order.