That $125 for the Aqua medic reactor is the best deal you're going to get. New calcium reactors are $300-$600 just for the chamber, $125-350 for a regulator, $40 for a ph probe, $50-200 for a co2 tank, $40 for a box of media. Calcium reactors are not cheap but totally worth it!
If you can find complete CA reactor setups for under $200 you should jump on them.