C02 equipment

[motoman]

I'm thinking about going with a pressurized C02 system  for my 20 gallon tank (going to upgrade to a 30 - 65 gal sometime soon) and was wondering if people here built their own or ordered online from someplace? Where to get them? What costs are associated roughly with the systems and what pieces are necessary. The systems at the stores around here are very expensive compared to what's on the net.  I've seen a lot of discussion surrounding PH monitors and solinoids etc. Also how are people diffussing the C02 in their tanks. I've made my own diffuser from PVC piping and screening but I've seen some with C02 kits that are like a gravel cleaner tube with foam and a powerhead attached to it to mix the C02 into the tank water. Any advise would be good.

[BigDaddy]

You can get the tank itself from a fire extinguisher company... there is one downtown (forget the name).  If you get a used unit, you can save big bucks.

The regulator and needle valve can be had online, or from brewing companies etc...

pH controllers and solenoids are not a requirement.

I've used the powerhead/gravel vac in the past, but now use the inline diffuser similar to the one in the articles on the front page of OVAS.