Don't loose heart; as other posters have said, walk-ons are your way forward.
Whilst you may feel that the costs are similar you get a lot more than just more paint for your money at a walk-on than you get at a pure "punter" day.
Don't underestimate the benefit of meeting and playing with like-minded enthusiasts; this really is a community and the people you will meet at walk-ons will at the very least offer you advice, help with your kit setup (if something goes wrong with your kit for example). They may have kit for sale that you can take a look at; and will be able to tell you other sites and events they visit to keep you playing and in the game.
Of course the biggest benefit at walk-ons is that the other players will have some paintball playing experience so they are far more challenging to play against; far more fun to play alongside and far more useful to learn from....
I've heard of a site up near Stafford (unreal paintball in Madely) that run a monthly walk-on that may not be too far away for you; last I heard they were £45.00 to play (and included 2000 balls) but I have never been.
Good luck, keep at it