$250-270 maybe more or less depending on the buyer and how desparate you are to get rid of it.
Paint it camo and give it some ghillie strips, put it on E-bay with a bunch of hype about sniping and watch the money roll in. If you market properly someone will be willing to pay FAR MORE than what it's worth.
I bet you could get around $170 for that on Ebay. You have to remember the countless amounts of other people on ebay selling their fully decked out Tippmann besides you. Surf ebay for your competition and then set a price.