Let's see...that answers those questions pretty well. First on this list is buy a nitro tank, a Freak kit, a 4 or 5 pod pack, and a Revo. These are what you want with any gun, and make anything complete, otherwise you will be lacking in areas you don't want to be. Then look at the money that you have left from that among which of these you can get at a bargain and/or used price, then shoot each of them for a game or two as opportunity allows:
Impulse, BM2K(2), Shocker, Sovereign, basic Cocker, Palmer Blazer, or MagRT (NEVER regular 68 Mag...I made that mistake once, and you shouldn't have to subject yourself to the same). These will keep you on the level with whoever you'll face without breaking your budget or your back. You make the call from there.