As of 12/31/2014 the 2013 silver proof quarter set sells out. Even though the 2012 silver proof set had lower sales than the 2013 set, taking all option into account that offered the silver proof quarters, the 2013 silver proof quarters are the lowest mintage so far. Sales as of 12/28/2014 were 605,984. So, if the last two days of sales are minimal, the 2013 silver proof quarters sales will be lower than the 2012 silver quarters, which sold 608,060. So, how will this affect the value of the sets that contain the 2013 silver proof quarters?
Huh. Guess I should have held onto mine instead of selling them in September. I took the gamble the maximize the wholesale value while there was still (in my opinion) an over valuation for the 2013 full silver proof set and the individual quarter set I had as well. Since they were a Xmas present, I figured it was all upside for me. As for the mintage #, I guess it may have an effect, but this market is not a vacuum and I think the real mintage of the individual quarters is much higher because you need to add the separate quarter set numbers and the numbers of quarters included as part of the full silver proof set.
These aren't low mintage issues and they really aren't "keys" if they are in such close mintage proximity. I doubt this affects the price at all.
The thing is that moderns have been in a general downward trend since the 70's no? The real question would be what will be the lowest mintage of these in 20 years? If the current trends holds, I am betting 2015 or 2016 etc could well be lower. If you like the coins buy them, but I would not play the dangerous game of "guess the modern rarity" unless its to pawn them off on Ebay as "modern rarities".
LOL, yeah if demand increases, then ....... For now these will enjoy the status of the lowest mintage, which usually gives them a boost. Will they remain the lowest? Who knows, next year may be even lower.