Pete...
Your cycle theory is plausable.....but, T206 have always trended up....i think if anything they would just level off, or trend up at a very slow rate....just recently, they have trended exponentially higher than average i presume....i do beleive these cards are a good investment....history has shown this well over 100 years....a timeless popularity fuels this set is almost an anomaly onto itself, that's what fuels it.....part of the mystic,....
t206 and caramel cards inmho are on two different levels....i m sure other collectors would agree....it's been also fueled by the wags...no comparison...ok ok shoeless joe...blah blah blah....
the ruths....the 33 naps....ojs .... etc etc...
i have not studied statistics in a few years, but i would love to see some hard core numbers/random samples and regression analysis to the ror on t206...historically........that would just solidify what i have seen in my micro cosm of a 14 year general"feel" for them...