Forget DIY CO2, Kelly. Go with high-pressure CO2. It really isn't as daunting as it probably seems at first. All you really need is:
CO2 tank (rent or buy, it's easy to do either)
Needle Valve (http://www.clippard.com/store/displa...sp?sku=MNV-4K2
With those four main things, you'll be set to go and once you've made the initial investment, it'll only cost a few bucks to refill the tank.
Fightin' Texas Aggie Class of 2004
37 gallon AGA Black Seal, Emperor 400, Ebo Jager 200 W, 100% Flourite Substrate, 2x55 Watt AH Supply PC Lighting (5300K & 6400K) @ ~3.4 WPG, High-Pressure CO2.