I agree with Charlie..... with an additional caveat... be prepared to pay serious money for a decent Mark. A car with a running engine may be drivable but that doesn't make it decent.
IMHO a decent Mark II, is a "driver" that runs nice and not in need of an engine or transmission rebuild. Paint and interior looks nice, is pretty much 100% complete, has minimum under carrage rust and no major item needing repair or replacement. Depending on individual condition and mileage I put the price range $50,000 to $75,000. More for cars that exceed these specs and are superb in condition, appearance and/or authenticity.
'56 Continental Mark II