Wanna Play Paintball, in Dillsburg, PA (15 - 20 miles north of Gettysburg, on US Rte 15) is a awesome field. They have speedball, hyperball, and woodsball fields, as well as scenario games from time to time. Sundays are BYOP, with all-day-air/CO2 for less than 40$. Check them out here: http://www.wannaplaypaintball.com/
PS> I play most Sundays, so if you're interested in having opposition and/or someone you can meet, I'd be happy to show you the field. Just PM me when you're interested.