My son is 10 at the moment. I bought him his jacket and trousers from a bike show. Cost me £50 ($100), but it's always cheaper at shows. So, imo, going the off-road route would be the way to go as he's already growing out of the gear I got him in December.
Trust me, the expense is worth the peace of mind when your sons on the back and is GREAT for father-son bonding. I'm off to the Thundersprint with my son this weekend, he's looking forward to the time on the bike more than the rally
