I live in Canada and I paid 550 USD for the steering wheel and airbag which I bought from a guy in the US. I got a good deal since just the airbag retails for over $1000 CAD from the dealer. Be careful though when shipping the airbag that you have to ship via ground because of the pressure contents and explosive nature of the airbag, they cannot be shipped via air. The install of the airbag is actually qutie simple, maybe a 20 minute job (it's just a matter of removing 2 torque screws for the airbag and one bolt which holds down the wheel), but I wanted BMW to warranty the work so I got my buddy down at the dealer to install it for me. He charged me only $35 CAD which was a steal since they charge $30 to reset the airbag light anyways.

The actual diameter of the sport wheel is exactly the same as the original wheel. It only looks smaller because the grip is actually thicker which makes the wheel seem smaller and is a much nicer drive. It also has the sport grips which I love.

A lot of people cannot justify spending that kind of money for a steering wheel but it makes the biggest difference looks and feel-wise in my opinion.