Oh boy! Another "KWA is better...no it's not" thread!
To the original question, if you're just getting into the sport, I'm assuming you want a good, entry level gun. The Echo1 or JG M4 platforms are really, really good guns that will hold up well on any field. G&G is also making a high quality M4 right now (look at their "Raider") that runs about $200.
From there, you can go up to higher performance, higher price guns (like KWA's, etc). But for entering the game, one of the above at $150-$200 will give you a great gun.