West Marine
I have a C-310 that uses the same size tanks. I went to my local West Marine store and they had some 10 lb. tanks that would fit in my propane lockers.They are painted steel--not aluminum. I'd be better off with aluminum, but one will run you about $150 or more at an industrial gas supply company. I got the steel tank for $50.00, then added extra coats of paint on the bottom to protect from rusting.