I am terrible with used car prices, as I always seam to sell low and buy high. $6-8k seams like a fair price, however that is dependent on location, economy, and other factors. If you have already talked to your buddy about $6k, then thats the price. If you have the asking price of $8k, then let your friend know that, and see what he offers. If its higher, bonus, if lower, then go for $6k