You will need a regulator (milwaukee MA957 is less expensive than others), check valve (get brass not plastic), diffuser/reactor, and co2
tank. Bubble counters and ph regulators are not needed. Solenoids are nice and usually come with regulators as a combo.
Here is a
Milwaukee regulator on ebay for $86.95 plus shipping and comes with solenoid, bubble counter, and even free tubing. I'd go that route.
I'd buy the check valve and more tubing (doesn't hurt to have extra) from Rex Grigg
. Aquabotanic has the check valve for the same price, but plus shipping.
I'd buy the co2
tank locally, just call and ask prices before you go buy. If you can't find one for a decent price locally, http://www.aquariumplants.com
tanks, but you'll want to have a place locally that will fill your personal tank.
A drop checker is good to have. Its an easy way to know if you have enough co2
in the tank or not. You can't always rely on pH/KH
because of things that affect those. The glass ones are nice looking, but not cheap to buy in the US. There are sellers on ebay that have them for $8-9 but they aren't in the US. Honestly I'd look for a Red Sea brand one and just get that. Cheap is better than fancy!
edit: Haha...Markstanfill and I were thinking alike.