1500 hunny per month I would have laughed at them you can buy them for 25,000. Are you locked into a contract with the current gas provider or just a verbal commitment? My tank costs 650 per month and I think that's even a rip off. I can't wait to dump my oxygen company in 4 1/2 years. A penny in your pocket is a penny in your pocket. Three cylinders is still 13500 cubic feet of product a week which isn't bad at all for a small guy who can get bigger. Getting bigger means more product used which is win for you and win for the gas company to. I would call praxair, airgas, or whoever is the largest supplier in your area and get a price. Product should be around a 1.00 a hundred for you. Here is the great part your current supplier is filling those 160's off there bulk tank and then delivering it to you and you are being charged to fill them which is labor then delivery so whoever fills there tank I would call but that's just me. I would cut there throat and leave em lying dead.