At $6 a gallon, that would be reasonable for a bladder tank. I was offered $1200 for my 200 gallon tank in 1983. I had paid $500 for it, wholesale OEM price as a boat builder. $6 a gallon would be a good price for a quality alumuim tank today. However the bladder tank is a limited use item, and I believe it has a shorter usable life. Many folks get the 30 gallon polyethylene drums for free or miminal costs--but I would rather the bladder tank. and who wants seventeen 30 gallon tanks in the cockpit. Bob Austin