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 2013, red tiger lotus, vals, java fern and moss, crypts, swords, mbuna tank: Yellow labs, Ps. demasoni, clown plecos, SAE's.
10g mini-reef. 16lbs LR, green mushroom, star polyps, wagon wheel polyps, purple mushroom, candycane, hammer, other zoas, CUC.