Rough budget:
New mask (worth getting new) - £40
2nd hand marker (like angel, e blade or impulse) - 3/400
2nd hand air - 1/200
That would get you a damn nice setup, and probably for about half the price that new would cost (resale very much favours the buyers here). A benefit of 2nd hand kit is that it should come with some upgrades already, which saves you the hassle of installing them.
An alternative would be to get a stock cocker, new or second hand, for about 200. Then you can upgrade it as you need and can afford. Cockers work splendidly for rec ball, and can certainly hold their own in a tournament, they're the workhorses of paintball. But...they can become money pits, so it could actually be more expensive in the long term.
Hope that helps