There was one around here aiming at high end corporate teambuilding - you wore full tactical gear and shot RAMs I believe. At least $120 per person per session - unlimited ammo included as far as I remember.
If you sold the clips with air at 3 clips for $10, you could make money.
Sell 15 co2 and $150 shots with 3 clips the rental reloads for $50 and that's a day of paintball for a rental. If you have 14 pistols and 40 mags, I bet you could pend $4,000 total and have a starting set up.
Getting CO2 sucks since you cant reload the 20 gram cartridges.