I know it's a pain. I searched for this stuff for a few days. Many local pool applicators refused to sell to me.
However, after a few days of digging. I found some sellers that sell 3M ColorQuartz T Grade for around $20.00/bag, S grade is a bit cheaper I think.
I haven't got mine yet, but now I know where to get them.
National Pool Tile Group will sell 3M ColorQuartz to you.
2840 E Miraloma Ave
6370 Artesia Blvd
Buena Park, CA
these two are in southern california. You can call them to find out other locations.