One thought is a digital language translater. The kind where you type in what you want to say and it tells you how to say it. I'm not sure what they run.
Also, you can find out what type of camera they are getting and get him a very large memory card or 2 for it since he won't be able to get somewhere to develop the pictures as often as he might like.
I've also seen small digital picture frames/displays that fit into a wallet. You could get him one and load it with pictures of the family for him.
Alternatively, and ipod loaded with his favorite music and pics of the family. (Might be a little over your budget.)
Another idea is some phone cards to allow him to phone home from wherever he is.
If you have others who would like to go in with you on a gift, you could look into a small handheld computer like the Dell Axim. They are a little more expensive than your budget. I believe they run about $300 but you could also check to see how much a PDA would be. Most of them have similar operations and some cost a bit less.
Hope this helps. Good luck to you and your brother.