Would depend entirely on the car.

No 2 cars are the same.

How badly do you want it,.. how badly does the seller need to part with it. What over all condition is the shell in,.. what comes with it etc etc.

I've paid between $100 and $2500 for different rollers.
Too many variables to give an accurate answer.

Reality is that its worth what ever your willing to pay for it.

Hurst