Most of the bench equipment I use is store brand, so I usually get belts, discs, and bits from local hardware stores (may not work for you but it works like a dream for me). For quality blade/tool steel, I usually purchase from Aldo (The New Jersey Steel Baron). For forge bodies/replacement hardware, I shop at onlinemetals; a bit pricey but they seem to have a greater selection of of sizes compared to what I've seen elsewhere, and also carry a few tool steels. For the forge lining and insulation, sometimes through high temp tools, other times through bailey pottery.