for the least expensive Mooney on that site, a 1963 Mooney M20C. It has metal wings instead of the M20A's wooden ones. That's both a plus and a minus. The metal wings aren't subject to potential rot like a wooden wing and it's a lot easier to find a skilled mechanic to work on metal, but the wooden wings are about 8 MPH faster (smoother finish) and have a much better ride.

The listed plane ( http://www.airshow.net/html/adpage.cfm?ID=6549 ) has over 1500 hours since the last major overhaul (SMOH). The Lycoming O-360A1A engine has a time between overhauls (TBO) of 2000 hours but not all of them make it that long. You'll be facing a very expensive overhaul (~$8000 to $10,000) within a few years. The last propeller overhaul was in 1996, so it'll be needing one of those pretty soon. That's cheaper than an engine overhaul but still isn't cheap. (Nothing about airplanes is cheap!)

The avionics are comperable between the two planes. Both would need about $5000 to $10,000 worth of upgrades to be ready for serious IFR, and that's if you use reconditioned radios.

The last problem with this particular Mooney M20C is that it's in Canada. I'm pretty sure you have to pay an import tax to bring a plane back across the border. It might not be very much but it all adds up. Still, at $60,000 Canadian ($38,400 US), it looks like a pretty good plane. Just be ready to pay for an overhaul pretty soon.