i can give you some general information on prices. basically, mini bikes aren't worth crap. that about sums it up! for example, the most i've ever made on a mini
bike sale is $10. Usually i loose money, like hundreds, when i go to sell. And it doesn't really matter if it's a fully restored vintage
bike, or an as-is 'survivor', i loose and i loose bad.
even Rupps, which are kind of that gold standard of mini
bike, don't seem to sell for a lot. i'm sure it happen now and then. For example, look at this 1969 rupp roadster on ebay right now... it's a beauty and it's many thousands. but it will sit there forever. the seller might get lucky, but from what i've seen, it won't sell. there was a guy on facebook selling nearly the same mini
bike for under $1000. He did eventually sell it... but man it took some time... Even black widows, which seem to be the 'hot' vintage mini bikes, have a hard time selling for "their valve".
bottom line... mini bike buyers are cheap bastards!
and with new (and decent) mini bikes available for $300, can you blame them?
unless you find that buyer that's, "i'm rich and i gotta have that vintage toy from when i was 10 years old", good luck!
also location drives prices a bit too. like the coasts seem to be more pricey. in the midwest minibikes are cheap.
I will say that vintage mini bikes with 2 cycle engines (opposed to say a Tecumseh Hxxx engine) do actually sell for real money. But those are not the norm. For example a Speedway Silver Shadow, that would sell for sure for decent money. but they made like 25 of those? It's not the norm.
that's been my experience. your mileage may vary.
Speedways are way cool. i've never had one that wasn't a total project. But as an example, i re-did a Shrike. Powercoated it, rebuilt Tecumseh H35, new series20 torque converter, it looked great and rode/drive awesome. Tried to sell it. $400, nope. $300, nope, $200 finally some interest, but ultimately, nope. I took the rebuilt and repainted engine and sent it to a friend (for free!), and GAVE the roller away to another guy (minus the gas tank and TC, i needed that for another speedway i was re-doing). He put a predator on that shrike with a standard clutch, and he and his kids are happily riding it. man i don't even want to think how much i lost on that
bike... and of course after i gave the
bike away, THEN someone wanted to buy it (mostly because they wanted to part it out for the wheels!)
the only guys that seem to make any money are those that part out bikes, and sell the parts on ebay. then suckers like me are at their mercy to buy their expensive parts. that's how i manage to loose so much money on mini bikes... buying parts...