It seems like it might really pay to get the phone book out and make calls and see what you can find.
When I got into co2, I bought a NEW 10 lb aluminum tank. First time I went to get it filled, at a local fire extinguisher place, I ended up leaving somewhere around $28. They said I needed some kind of stickers on the tank, which was 3 or 4 bucks of the total.
Second time, I went to the same place and it was $23 just for the fill. Still seemed a bit steep.
The other day I saw my tank getting low, so I started to call around. I tried Airgas, but they only exchange. I'm almost sorry I didn't just get into that. But now, it would be hard to watch my pretty, lighter aluminum tank go away and end up with some clunky old steel one.
Anyway, the guy at Airgas was still very helpful. The place I had been going is right up the street from them. He sort of laughed a bit when I told him I went there. He said best to stay away, they sort of like to rip folks. Then he gave me a name of another place a couple miles away that is filling my 10 lb for $8.