If he's an outdoor type, I'd strongly recommend the Ka-Bar Becker BK-2. It's built like a tank, made in the USA and comes with one hell of a warranty (lifetime).
I like ESEE knives, but find that the slab scales are not very ergonomic, though I do like my paracord-wrapped Izula. For a modern style folder, I'd suggest a Spyderco Para 2, but I think it's a bit over your budget; great knife though. As far as traditional slipjoint folders go, I'm a big fan of Great Eastern Cutlery, you may be able to find one of their tidioute single blade scout knives with nice bone scales for your pricepoint.
Good luck researching, and let us know what you end up with.