After some discussion in chat about it, and meeting up with a paintball wizard... I can say for sure - using paintball CO2 bottles for planted aquaria is definitely on the horizon.
I say this because I found a source, and some rough pricing on some custom work...
Problem as with all manufacturers - is to make it worth their time and effort - they want a substantial minimum order (this case - 150).
How many of you out there would be interested? For rough estimate of 40us$ you'd get a fixed regulator, very fine adjustment needle valve (According to the manufacturer, they will do as low as 1bpm), and a tank side pressure guage. Just the basics - I'm sure one can add solenoids etc later if they wished.
Advantages: Basically initial price. Pressurized system for 70$us (20/24 oz paintball tanks/bottles are under 30$) Refills might be a little easier to find for those in areas away from industrial sources. Size could make them an attractive option for those with nano tanks at the office... And there is the bling factor - after all, no exchanges - so blow all the $ you want on a fancy bottle
Disadvantages: Long term cost - refills for the little bottles run 5-10$, and they wont last near as long as the 5lb you could get refilled for about the same price... Otherwise, it's basically the same system.
So, what sayeth APC?