Jay, so many variables in the VREF...you may be better served doing a discrete VREF calculation based on your plane - and I think AOPA has one?
Our 50-year-old planes are now so remarkably different as they have changed hands literally a dozen times each in most cases...they are MORE unlike than like each other now with all the mods, TBOs, STCs, TLC, etc., etc.
While I think it is good you are asking for the fun of it, I am not sure it will provide you any fidelity or accuracy -- but may provide "very rough ballpark"? (of course, you already knew that)
I sometimes go to BARNSTORMERS to see what asking prices are for M Model C-150s. The spread is all over the map...based on the myriad of variables, conditions, upgrades, etc.
A couple of years ago I tried to help a widow sell a C-150 and another widow sell a Chief. Of course, they went and looked online and found HIGH END of both...and both wanted $35-50K for their husband's planes.
However, the planes were NOT high end and eventually sold for $15K and $10K respectively. (they sat because the price was too high, then sat so long they went "un-airworthy" and the prices DROPPED more)
