Yes, I agree that some people chase the 2006 set as an alternative. However, I suspect the demand come from people who get/like the 2011 set and then realize they don't have the 2006 so they must get it and there are people like me who think it's becoming a series and want to get the "first coin of the series" to complete it...
When the 2006 came out, it was a stand alone set, as time dwindle, a portion of the mintage is removed from the market (natural attrition via gift giving, storage, loss, damage, etc) so even though the mintage was 250K, the market wasn't flooding with them.
The RP of 2006 was/is pricing on par with the 2011 RP (100K mintage, only 40% compare to 2006's 250K mintage). Another note: Before the release of the 2011 set, the 2006 raw set was still going cheap, only the graded one are pricey.... after the the 2011 set release, the 2006 raw set increase in price faster and a lot more than (compare to the graded 2006 set).
I don't think the 2006 set and/or the 2006 RP will increase in price significantly. The highest potential is in the 2011 set and its RP with the lowest mintage. The 2012 set and RP is a sleep for now and will probably only appreciate in a year or two. The 2012 set is plague with quality issue so the raw/69 set will always available and the price should stay reasonable. In the long run, the graded 70s of the 2012 set will probably command the highest premium.
If anything, look at the mintage of the Burnished -W
ASE mintage of the last two years for some clue. I think the Burnished
ASE mintage is an indication of the number of 'hardcore
ASE collectors' and would expect the same range of mintage for this set. However, as I've mentioned, with the current silver market condition, we should assume a weaker demand for this set than normal.
Lastly, something that's unwanted today but have a large base of followers may catch fire some day latter on and become valuable. Just look at the 1995 W
ASE, it was part of the gold set that's selling for $999 (very expensive, considering spot price at the time)===> not many people want/can afford it leading to only about 30K sets made. So, when the dust settle, the 1995-W is the most sought after coin with the lowest mintage that worth around $3K.