Unless you can get a 232 really cheap and you live very close to a dive shop (for air) then your better off spending that little bit more for a 300.
They stay in test for 5 years, so make sure the one you buy is in test or cheap enough to justify the cost of a test. (Don't buy a carbon bottle, they are being phased out due to safety worries)
Anschutz 2013 MEC1 .22LR
Miroku 3800 12bore