Base looks new to me.
Bonus mechanism looks like it came from a hightop Bonus and not a Horsehead Bonus.
Regarding fair price. That is between you and Frank. However, you might be well advised to spend the 4 bucks on a price guide (
http://www.AntiqueSlotMachinePriceGuide.com subscription to see what these and others have actually sold for. If you don't want to do that spend some time searching eBay and see if you can find any that have recently sold.
It could save you thousands. If you do look on the price guide do a search for "Horse Head" and "HorseHead" (with no space).
Full Disclosure: I run the price guide.
Dave