If it's an HO scale car, about $2 for the Kadee couplers and up to another $20 for the other stuff you need to mount the coupler (2-56 screws, pin vice,a #50 drill bit and a 2-56 tap). If you already own a pin vice and the drill bit and tap, you'll spend maybe $4 overall on the car.
If it's something else (American Flyer, Lionel) - you might have a bit more trouble.
-Dan
Builder of Bowser steam! Railimages Site
how much is it to convert a link type connector to a coupler. i found a really nice old box car with a link type connector and would like to make it a coupler.
thanks