Refurbished MacBook Air would be my recommendation.
I say one of them, because they are quite cheap, but its the OS i think he will benefit more out of. I will admit, that i have trouble finding my way around a Windows OS, and i think myself to be quite computer literate.
The Mac OS is simple, yet powerful, and things are in a logical place.
Pictures are in Pictures folder, Movies are in Movies, Music in Music, Documents in Documents . . . . . See logical.
Window My computer, C Drive, Files, Documents ??
But if he is looking for cheap then its the Netbooks, but you can pick up a 2011 MBA 11" for $600 . . .
Then again as our friend above me said, a iPad could be what he could use, depending on why he needs it.