You are on the right track with your comments! The U.S. Mint has been caught off guard this year with plummeting precious metals prices, especially platinum, but gold & silver too of course. They obviously are limiting their exposure by just making a small offering on these platinum Proof coins. They also have abruptly stopped sales prematurely on the 2015 Proof gold Buffalos this week without notice. The Mint has set mintage limits on a number of coins this year only to change them when precious metal prices fall. They have also called a “Sellout” on coins/sets which i know from my new Memphis fulfillment center contact that they have a few more of but don’t want to bother with due to a complex but inaccurate inventory/sales structure (it typically takes 2 years to get final audited sales figures!) & they resell coins returned that have small quality problems instead of destroying them as per standard operating procedures. This is what happens sadly when the Mint outsources almost everything these days, including most blank planchets, packaging, customer service, fulfillment center & more! I expect more from the largest Mint in the world, but unlike most foreign gov’t Mint’s that are run as true corporations, we in the U.S.A. are stuck with a Mint that is a bureau of the U.S. Treasury Department & full of the typical Washington D.C. bureaucracy. It is unfortunate because the Mint has so much good potential.

-NumisDudeTX

The U.S. Mint website has a section labeled “Product Schedule” with a toggle function you can choose “2015” or “TBD”. The 2015 Limited Edition Silver Proof Set is still listed as To Be Determined (TBD) with the item # you mentioned & a blue “remind me” button you can click on to receive an email when or if this product is issued. The 2014 version of this set was not issued until 2015, so i wouldn’t hold my breath as to when or if this set will be issued. But, at $139.95 for the 2014 set, which is still available, i bet the Mint will be glad to take our money again for such a set issued every year starting in 2012. Although the limit has always been 50,000 sets, sales of the most recent 2014 set issued in 2015 are far from a sellout.

-NumisDudeTX