I paid $16k for my 63 M20D, which is IFR certified with basic 6-pack and a "run out" engine.
I've probably for $45-50k into it by now, and if I sold it today it probably wouldn't get maybe $25k for it. I highly, HIGHLY suggest paying more up front, it will make it worthwhile so you don't spend the next 11 months watching your "new-to-you" airplane doing nothing but sit in a hangar and be worked on all the time.
If you're seriously interested, my friend has a 1964 M20C, 400SMOH, nice flying airplane, needs some radios for $35k here in Florida. PM me.