At a dealer in Pittsburgh, they have a 2000 740iL listed for $32,900.
Another one in the same area has a 1997 listed for $15,900. Of course
private sellers may be less and you may be able to haggle with a dealer.

Check out the BMW site, enter your zip code and a mileage area you are want
to look within. It will give you a listing of the dealers and you can search
their inventory.