How to buy a wildernest?

Hello guys and gals. I Found a wildernest here in SoCal that I am thinking about getting. The guy who has it seems really cool and hippie-ish and is willing to trade stuff instead of taking cash. My question is how much would a fair shaped specimen go for? I cant think more than 500 dollars or so, but I need a value amount so I know what to bring to the table. Thanks for any help and suggestions!

Ive seen pretty decent ones go for $700-800 Id say fair condition $300-500

Yeah, they don't make them anymore so the price would depend on condition, especially the difficult-to-replace parts.