I've bought airplanes off salvage auctions and bid on many more. My experience has been that the buying process is hit and miss. Airplanes that are in good enough condition to essentially fly away with a little work usually seem to get bid too high, as do the prop strike and fabric covered planes. Complex airplanes and really wadded up metal planes don't seem to bring much value and you're likely only bidding against the salvage yards on those planes.
Pricing wise, do not get so attached to the idea of buying the plane that you overbid it. Look at the major components and their value, and bid that much. Once you sell them you'll have the rest of the plane to make your money off of, which may take years to get.