You can try Field 51 in Gorham (near Portland), it is a great field and for the time being it is free. The owner, Norm, used to run Rangeley Paintball, but is now doing it closer to his home. They are still waiting full approval from the town (which is why it is free for now), but he still runs games fairly regularly. You can check them out at
Field 51 Woodsball Paintball
Where are you located? I play with a group of guys in southern Maine and NH.