That is a hard question to answer.
Are you looking to flip it and make a profit? Are you going to do the repairs / restoration yourself? Does the machine even need to be restored? If it is a nice original then you should not restore it. I recently SOLD a restored Rol-A-Top on ebay for $3,200 and BOUGHT a very nice unrestored Rol-A-Top for significantly more than that (from a private party, not ebay)
If you are going to restore it yourself then you should know the Rol-A-Top is one of the hardest machines out there to restore properly. If you are going to pay someone to restore it then that will not be cheap (assuming you go to a legitimate person who knows what they are doing).
Go to
www.AntiqueSlotMachinePriceGuide.com and look at what they have recently sold for.
If you could post some photos then that would be great.