I would get him a scx10 II kit ...he can work on it,can choose whatever body he wants, its cheap and a decent crawler .
Lipos are good ...17.5T/13.5T motors not so much !
For crawling you better start with a 27T brushed and a crawler ESC for low speed control. A Holmes hobbies 27T trailmaster on 2s and a HW 1080 is like 60 bucks...peanuts. Have fun you two