pafitz, nice you're from the Burg

If you're willing to try an alternative method.  Try the clusterbustering route using rc seeds.  I think I paid $12/100 seeds and they give you way more than 100.  I had a shadow yesterday which is the same sign you're getting to prepare for take off.  If I take seeds when I get these shadows it's possible they can calm a cycle or crack it all together, however that's just for your body to decide.  If  you choose to do this, read everything possible on Multimedia File Viewing and Clickable Links are available for Registered Members only!!  You need to or

Anyway, you asked about O2.  Here is what I paid.
$21.95 for a 0-15 LPM regulator (CGA-540), $27 and change from here for the optimask and $36 for an "M" tank of medical grade O2.  Do you have a script from your doc?  If not, maybe you can go with the welding O2 like a bunch do on here. 

Best of luck!

Cheers,
Chad