I have 2 geminis and am wondering what they are worth? i believe they are 80cc but they may be 50cc.
Right now, as far as value, anything being sold is only worth what soebody in this economy is willing to pay, certainly not what something sold for on ebay or CL a couple years ago...
Take EVERYTHING into consideration, one thing I can tell you is do not overpay for anything right now, there is stuff, nice stuff for cheap all the time. Its not worth it to overpay for any mini project right now, you will end up spending way more than if you stay patient and find one thats in great shape.
One thing I can say about Gemini's is you dont see that many of them around, that being said make sure everything is all there and running if possible. Gemini parts appear to be very hard to come by. I think they are cool as hell, my cousin had one years ago, wish he never sold it! Didnt know what he had I guess.