I have at present 8 main tanks-4 steel 72's, 2 lp95's, and 2 hp 80's. Along with a 19 cu ft pony and 40 cu ft stage. Add to that two argon bottles for my dry suit and you have a little money wrapped up in them. However I did what many have suggested and bought used except for my 19 and the 2-80's. My 72's were 75 bucks each from the shop. My 95's I got when I met a guy in Key Largo who was getting out of cold water diving and did not need them anymore. Price- 200 bucks for two 95's with bands and manifold. I sent him 300 because it was such a good deal. Plus 68 dollars shipping from minnesota to pa. Now since I work for a shop I get free air including nitrox, do my own vis's, and the owner does not charge me for hydros. So for me buying was really a no brainer. I always have at least 4 filled at any one time and so there is no waiting whenever I want to go. Plus even though we are switching to steel for our rentals we had mostly aluminum and I prefer to dive steel. Our rental al's we sell off as we add the steels for 100 bucks. This includes new hydro, vis and fill. Buy a couple and we can deal a little more. I'm probably going to end up with one for a stage deco bottle to add to my 40.