http://www.customaquatic.com/customaquatic/pic12.asp

http://www.myreefcreations.com/main.html

And several pumps:
Circulation pump( Mag 2, Eheim, etc.)
Feed Pump ( Gravity, Maxijet 600, etc.)

About $5 to $10 to fill a 5 pounds Co2 bottle.

For safety purpose, certain reactors should be used with a pH controller.