Those two remaining pulleys that the manufacturer had are now sold. I bought one and another forum member responded to take the other.

I am still willing to coordinate another group buy as the manufacturer is willing to produce another run if we can get 10 buyers. Post here if you are interested.

The manufacturer also told me that his next batch can include a special "friction coating" on the grooved part of the pulley for better belt grip (possibly eliminating the need for more belt wrap).