If you do not know much about the internals and how to do it yourself, I would leave it be. If you know you can do it all yourself then you have a chance, but no big profits will arise from such a small bike. Like mlatour said above; look at bikes for sale on the internet near you, and decide how well priced it really is. Based on your question you seem confident its not a real deal. make sure your committed either way you go. Maybe convince him you can fix it if the price gets raised and you split profits when sold.