Well, you can bring the gun to a game to try it out. Just don't be surprised if it doesn't last the full game. But you may be able to borrow or rent a gun at a game anyway and it'll give you an idea of what better guns are like. Often there are ASC age verifiers at games, so you can take advantage of it to get verified.
At first glance, all airsoft guns may look more or less the same. But you really get what you pay for. There are good starter guns, but expect to pay at least $300 off the hop for that.
And yes, an RC car charger is a good start.