As has been stated, get AV'd and the world opens up to you.
If you absolutely won't be dissuaded from picking something up on the extreme cheap, might I (and I know others would echo it) recommend the Crosman Stinger S34P? It regularly goes on sale (looking online, it is presently 119.99) at Canadian Tire for cheap, and it's a decent clone shotgun that you could actually keep using once you get into airsoft for real. Throw a coat of black paint on it and you're good to go.
And trust me, speaking as a former paintballer, you will get into airsoft.