Good link foob4r.
Schikitar you need to read that link before doing anything like storing gas. Apart from it being a lot less pure than many might expect (actually having enough O2 in to cause the problem you are trying to avoid), there is also the risk of infection so I would put an HEPPA filter between any stored CO2 and where I wanted to use it.
The reality of brewing is often much more complex than would appear to be the case on first examination. I really think you need to look at the real costs, there are plenty of safe ways to save money, storing CO2 isn't one of them.
If you really want LoDO in package, filling the keg and blowing out with CO2 is really the best option, just don't use an O2 based sanitiser…
Mark