I'm thinking about purchasing my soon-to-be-coming-off-lease 2005 X54.4i and my dealer has offered to purchase it from BMWFS, certify it, and sell it back to me at a somewhat reasonable price (less than the lease residual value). Can I shop this around or do I need to go through the dealer that initially leased the vehicle to me? I'd like to see if another dealer could do even better.