What paint were you spraying? I assume it's 2-pack as I think I can see the hardener in the background - that mask is no where near suitable and you can absorb it through your eyes and skin and cause you to become crippled by asthma. I wouldn't want to see you in that situation.
If you do want to spray it safely, I can PM you the details a bloke that sells firefighter BA sets through eBay, the canisters last 30 minutes each and are refilled at £4 by any scooba diving shop. I bought a set with three canisters from him for £75.
Loving the DIY spit though, wish I'd made one for my mini!