It's been said before, in terms of playing poaintball it's not too expensive. Pay for travel, and about £50 for a day of playing, it's a bit of money, but could be much more! Most of the cost is in the poaintballs itself.
The real problem i've found is starting poaintball is getting all the equipment! In the last 2 years of starting, i've spent (on a rough calculation of what's in my kit bag at the moment) over a thousand pounds on kit, and that's not including however much on tournament fees, paint, travel costs, hotel costs etc... Now for those in full time employment, that's not so bad, but for a student who only has a part time job on top of having to pay for rent and living costs, as well as the rest, it soon adds up!
So once you've gotten deep into the poaintball life, it's not as expensive as people think, it's just getting to that comfortable stage in the first place