Can anyone honestly say....

[brewing]

There were 2 sets I built where I acquired large lots at a great price as foundations. Filling in most of the holes with a couple of lots and the rest over a 2-3 year period.

In those 2 scenarios, I made about 20%

I sold most of my other sets 5 years ago (from break even to 20% loss), if I would have waited until this year I probably would have done quite well.

I think it depends on how long you hold it and how vintage it is. Sets from the 70's are price losers when selling as a set.