Check out Kee's line of Paint. I believe they sell a reball in cases of 2000. Also, if you're looking for a marker that's easy to use/set up/repair/clean, Cheap, and can be stored longer periods of time without issue, You may want to just go and grab some Tippmann 98's.
They'll keep running until a few years after the end of the universe, and might even survive in the hands of Doc & Crew. Be cheaper than buying pistols at the very least.