[mps9506]

I haven't heard much about their calcium reactors. They look pretty similar to the design of other successful calcium reactors so I imagine it works fine. Might want to do some searching for reviews on it though.
A quick search on google and it appears you can purchase one for about $250.
Co2 tanks are available at a lot of places, I would check your local welding supply place for a 5 or 10# tank. The regulator will run you anywhere from $75-$125 bucks or more depending on the quality and brand. You will also need a pH monitor or controller.