$800 is a lot fora non-running 10-yr-old bike that has possibly been wrecked. Typically, if it’s was so easy to get it running, the seller is foolish not to do so. Even if it runs rough, it ads significantly to the value. So that tells you that the seller is either grossly underestimating the work needed (ie. possibly lying) or he is lazy beyond believe. Neither trait is desireable in former owners of your next bike.