I got them from Upscale Audio. Shipping to me is ridiculously fast. I decided to get the Gold grade. I did not feel it was worth paying extra for the Platinum grade or "Kevin's Stash" since I believe that is more or less just a money maker for them. I personally believe the gold pin version is important (that is all that Upscale sells, other venders sell a lower variety), especially with the McIntosh since the the tube sockets are also gold receptacles.
First listen last evening it was an instant noticeable improvement to me. Of course, your mileage may vary. For me it was the largest improvement for dollar spent ever in this crazy hobby!