I use PFS, have for a while, and there are worse things than paying $0.80/lb. I've been looking through alternative substrates available locally, and I'm a little lost. I have a properly sized (20-40) Coal Slag product available, but the MSDS lists a bunch of metals. The more expensive one is 35 grit and says Stable/Insoluble. Otherwise I could go with a PFS sized 10-20, or a Pure Silica Sand sized 20-30. All of these are 0.25-0.35/lb. Does anyone with experience with these have any suggestions?