What is a parking spot worth?

It's hard to put an exact price on a parking space in different neighborhoods; when new buildings are sold, parking is often negotiated or "free parking" included if the building wants to hold firm on their prices. There is currently a one bedroom listed in DuPont (18th and Q area) with a parking space available for an extra $47,500. Seems higher than I would have estimated but it is quite a luxery to have a spot in DuPont.