You are not thinking rationally.

That car is a potential money pit. 500 miles a month? And you only need 'some car' until Feb 2013??? RENT A CAR. 9 months, rent something.

Or go to swap a lease, pick up a car for a year.

Owning a used X5, sold at auction, is a real risk without a BMW Platinum warranty- and THAT costs $4500. (Or $450 per month that you will own it.) The dealer is probably offering a cheap powertrain only plan... (That simple seat switch could be $700...)

Finally, you want to put running boards on?!??! For 9 months? Nuts.