+1 on the $1,000 in parts.
I had a Maruzen one upraded pretty heavily a while back. Was worth well over a thousand bucks. The advantage you get it still not really worth it. You aren't ever going to be pulling off uber 1337 sniper senario's like in movies or some shit. The range advantage is just a bit more. Then accuracy is just a bit better. But what does that matter when you miss your first shot and your enemy barrels down on you with 20 less accurate shots....
I'm not saying don't try it. But do remember, it requires some skill and effort. And the big thing is, again, your weapon does not really give you any advantage in airsoft terms here.