Join Date: Jan 2008
In terms of pressurized CO2, a larger cylinder may be more suitable for your aquarium.
I believe the JBL CO2 kit that you are referring to only comes with a 500 gram CO2 cylinder, which will last 2-3 weeks at most on your aquarium. Refills for a larger cylinder are usually not that much more expensive (prices rarely increase linearly with weight).
If you are going pressurized CO2, there are a multitude of commercial solutions. In addition, if you are feeling handy, you could also source the parts yourself and assemble a CO2 kit (for this route, or just for more information regarding pressurized CO2, please take a look at my Pressurized CO2 Primer, linked in my signature below).
Finally, regarding refills for pressurized CO2: you can usually refill them at paintball shops, welding shops, stores that cater to home-made beer, etc