Thought I'd share a couple of tanks I just bought on Ebay. One is a 2003 and the other a 2004 that still have a active hydro life left in them. Both are in great shape and he'll make you a deal on shipping if you get more than one. I know the tanks are close to end of life but for $275 for both shipped I thought it was a pretty good deal, lots of shooting for a couple of years. The seller "baseball 1998" was very easy to deal with and responded to questions very quickly. Here's link if your interested.
JK
http://www.ebay.com/itm/Scott-4500psi-45min-Carbon-SCBA-Air-Pak-Bottle-Cylinder-Breathing-Tank-Mfr-2004/191771821852?_trksid=p2045573.c100033.m2042&_trkparms=aid%3D111001%26algo%3DREC.SEED%26ao%3D1%26asc%3D20131017132637%26meid%3Dc92891f77d9544048834b8d26958f725%26pid%3D100033%26rk%3D1%26rkt%3D1%26sd%3D191771821852
JK
http://www.ebay.com/itm/Scott-4500psi-45min-Carbon-SCBA-Air-Pak-Bottle-Cylinder-Breathing-Tank-Mfr-2004/191771821852?_trksid=p2045573.c100033.m2042&_trkparms=aid%3D111001%26algo%3DREC.SEED%26ao%3D1%26asc%3D20131017132637%26meid%3Dc92891f77d9544048834b8d26958f725%26pid%3D100033%26rk%3D1%26rkt%3D1%26sd%3D191771821852