Some of the factors to consider is whether it still has the 6,2l and 3 speed transmission, or if it got upgraded at some point in it's life to the 6.5 and 4 speed.
Pictures of the doors would give us a better idea whether they are aftermarket, or original military doors with the supplemental armor on them. The original doors are worth around $3500-$4k just by themselves, aftermarket would be less, maybe $2-$3k depending on style/who made them.
Not knowing any more than you told us, I'd expect it to be worth anything from $10k with 3 speed transmission and aftermarket doors, up to the $20k range with military doors with supplemental armor, 6.5l engine, and a 4 speed transmission.
That's more for my area though, not sure so much what the market is like down there.