I've bought a number of turning blanks on eBay. I've had a couple that weren't real great, but they've always been as they were described. (The "not great" pieces were spalted wood, and to his credit the seller said they were punky and would be tricky to turn.) I just pay attention to the shipping charges, and bid no more than I'd be willing to spend for a piece.
Haven't bought any lumber there, though. I'd think it would be about the same...know your shipping costs up front and factor that into the total price.