A lot more than a hard top frame is worth even though it will fit under the hard top, the sedan, and a convertible. The reason is it is stiffer. Stamped out of heavier gauge metal, and it has two additional cross-members that cars with rooves don't get.
A convertible frame has to be strong as it is the only thing to keep the car from snapping in two when you open the doors.
As to cash value I haven't a clue, as I never bought one.