ive got an old Emaxx (is old now in terms of modern stuff) but its a Lot of fun! have completely Blinged it up too and gone mental with the motor, (had too as all the extra weight slowed it down a smidge haha)
but would defo recommend an elecy one to start with as you can get used to it int he garden local park with out annoying the neighbours etc.
with the good batts out now you should see 1/2 hour run times easy and modern chargers means they dont take all that long to recharge,
a lot fo fun to be had! as the toher guys have mentioned, best to stick with the more known models like tamiya, traxxas, hpi etc, (the ones that pop up in most the online shops) as spares are a lot easier to come buy,
and i agree that a build it your self kit one would be a great present as you can build it with him etc.
making me want to fire up the battery chargers now hahah!
funny that seems a lot of mtb'ers also have rc trucks etc too!