What does he use to write? Just Open Office or Microsoft Word? Google Docs?
If you JUST want to type, anything will do. A $120 Chromebook will do. Get a USB keyboard that is comfortable to type on.
If you want everything else, I really like Dell Outlet - off-lease, 3 year old business laptops. Latitude, not Inspiron. They are just so much better quality than any of the cheap shit you'll be getting from HP, Acer and the like.