I know this doesn’t make for a great gift for the party, but some sort of IOU would prob make the best gift in the end. You could maybe get him something little for the party, but unless he’s been to wherever he’s going before, you have little chance of getting him something useful, even if you ask him what he wants. I think anything to make his life easier during the deployment is the best gift.
For example, he might want an Ipod to listen to his favorite music, but it turns out that one model turns to a pile of crap in the heat and sand. He might not know this until he gets there. Maybe he gets really homesick and misses . Maybe he needs a piece of gear to keep him alive e.g. better helmet straps, sunglasses, webbing…
I think it would be cool if he knew he could go to you first to ship him a luxury or survival item.
…or just go with the prostitute idea.