I just got mine from a National Welders shop in Charleston. They are based out of Charlotte, so there is probably a shop near you. 5# tank was $65, filled for another $11. Probably not the cheapest, but other places only carried 20# tanks!
72g bowfront planted, CO2, 2x - T5HO, Eheim 2213 and 2217, restarting after a move.
2g Mac-quarium. Clown gravel, fluorescent plastic plants, and 2 guppies.