Shrimp are more susceptible to CO2 than fish are.
Just remember that CO2 isn't cheap. Long term, yes (if you do it right), but short term, not at all. On the other hand, if you skimp now, you'll pay later. Up to you. But my advice is wait until you have $200-250 to spend, all told, on a CO2 rig (including cylinder). At that price point, you can buy something that you'll be happy with for a lifetime. The price point you're at now is only a sinkhole. In a year, when you finally realize how much better you could have done, you'll spend twice that amount for a good system.
Pay it all now, or pay half now, and double later. Up to you. I'm not saying paintball isn't the way to go. I'm talking about the regulator/solenoid/needle valve. Cheap products now are garbage later, and there's no upgrading garbage.