Blowback is a gimmick more than anything. As far as I'm concerned it's just one more thing to break on an AEG.
For a G36 I'd go for a Classic Army one.. but it will cost you $500 - $550. I've had mine for 3+ years now and it's still my primary. I've heard good things about the Gen III SRC ones but I haven't examined one personally.
And don't waste your money on CT guns. They're not even in the same league as the airsoft guns we play with, and you'll be so outclassed at a game you WONT enjoy it.
Just be patient and save your money.
"Someone in a Prius tried to race me at a stop sign the other day. I couldn't believe it. I had him for the first 100 feet or so but I can only walk so fast."