The polarstar system is magnificent if you are looking for the absolute top of the line in airsoft tech, but if you're looking for the sensation of the rifle gently kicking into your shoulder, and the bolt locking back at the end of the mag, GBB ftw lol. In terms of gas, it isnt expensive. I get 2 bottles of camp-stove propane (green gas) at walmart for about $6, and that usually lasts me about 4-6 months of random matches, and the testing I do on the WA M4 I'm building. The only issue you will have with propane is that it doesnt have the silicon added like green gas does, but there is an easy fix. If I find that a mag won't hold pressure, I put a bit of heavy duty silicon lubricant in through the fill valve, and after allowing a few minutes for the silicon to work its way into the seals, they're tight as the day they came out of the factory!
If you want to, I might be trying to organize a random match sometime soon. I can let you compare between electric and gas while we're out that day so you can get some experience and trigger time with both =)