Unless things have changed since I went through basic (15 yrs ago so they may have) a 12" plastic ruler and tweezers were two of the things I used the most. Clothes has to be folded to specific specifications with all edges lining up (thats where the tweezers come in handy)
Also, I'm not sure if they still where the black combat boots that need to be shined or if every branch weres the fabric beige/desert ones now but if they do where the black ones then cotton balls and shoe polish is a must too
Not expensive stuff but things he'll need for basic. I like the idea of an airplane ticket to come home, usually if you can afford it, you can come home before you head to your permanent base.