Thanks, I hadn't actually been that scientific about it. I'd estimate the temperature I was using to be well in excess of 50C, I'd say 60C would be the minimum and at times surely more than that. I'll measure tonight since I have a thermometer. Sauna temps are from 60-100C, or up to 200F, as hot as you want basically. I know in high temps you have to be careful with your breathing or you'll scorch your nasal passage or throat, which can be very painful.
As for building a sauna, I have a MIG welder so the stove will be a propane tank, tire rim, and scrap. The frame will be 2x4, polyethylene exterior and aluminium vapour barriar interior. Hopefully I can afford insulation. No panelling, 2x4s for a bench, and I have stove pipe and chimney donated. So it could be pretty cheap, I'm aiming for $200.