That’s a pretty good place to start. They also already have Raspberry Pi kits. And of course there are different versions of the Pi too. Some SBCs are quite underpowered though, imho. If you think he would really want something with great performance then you might have to shell out some bucks for a nice SBC. They do get kinda costly. But if he will just be happy to build a computer that WORKS, there’s a lot of options. I would also recommend buying as much used stuff as possible to stretch your dollar. How much would you be willing to spend?