Need a value on a Gold Cup

[Robb]

What's a realistic asking price for this guy?
Series 70, some add-ons done by Ikey Starks of Sports West decades ago. very limited round count.
GunBroker is just too all over the place, looking for a realistic starting point.
No box or original take off parts. I bought this in about 1985, still have the receipt.
Nice gun, no issues, I may regret letting it go but don't really need or shoot a dedicated range toy.

Thanks