RE:RE:sellingBelardo, Ridiculous... Thetford and Alliance are asbestos laden. Costly to mine and process, and hazardous materials. Good luck with these. Try out the Aussie flyash Co for another of these variants.
Baymag has a low cost deposit and seems good but there is room for two. Not much info on Baymag but it seems focused on non-structural so both have large niches.