Swap meets for cylinders. A fresh hydro only costs $10 at the welding store. My current little tank was a CO2 fire extinguisher. The welding/gas supplier changed the top valve, presto- a dinky CO2 tank. We also have a larger (20#?) tank at my work shop (custom furniture) for running air tools on job sites. I think it cost $10 at a garage sale. Sometimes used, but full, tanks can be had for less than cost of a refill.
So far, I've had more experience thinking than I've had brewing....you don't think they are mutually exclusive, do you?
57 batches so far,
33 wine, mostly Loquat, peach, plum, prickly pear
22 beers and ciders
1 Tequila, from a prickly pear wine experiment that didn't work. I call it "Prickly Heat"