The obvious one that spring to mind is a young tortoise...
Plus points: Hardy if looked after properly, veg eater, long-lived so will be in the family forever!, lovely little characters, generally fine with being handled.
Downside: Expensive, needs proper viv conditions, will outgrow tank over time, need constant care in terms of cleaning out, feeding and fresh water provision, as well as vitamin provision; long-lived and therefore a commitment.
An Iguana or Water Dragon are cheaper and have similar for and against points...
I'd take a trip to your nearest exotic pet store and let the lad have a look around, chat with the staff and see what he thinks...
Last time I went, they had Pygmy Hedgehogs. Super expensive but so beautiful - good job I'm skint!