I'd say it really depends. If I could find good clones in my area (which isn't likely) I would pay a good bit if the genetics were right. The thing that I have always heard about Blueberry is that you really have to search for a gem of a mother. If I am not mistaken, Blueberry is an inbred line, so there are lots of phenotypes. If the seller has really searched out that magical Blueberry mother that produces decent yields of that sweetest blueberry, I would pay a lot. If it's just a seed he popped out of a seed pack, I wouldn't go to crazy over it. Have you smoked the weed?
Either way, if the guy has extra clones, he's probably not too worried about it unless he's a serious commercial grower. But then again, he wouldn't be offering at all if it's his corner on the market. I would pay $50 if it's pretty good. Just try to buy one and make a mother. Wow, I'm really stoned. I can't believe I responded with all that.
D-Town