OK, thanks again to all contributors. There are a few considerations, however, that need to be kept in mind:
It's not a given that my son will be interested in reloading. I didn't reload that much when he still lived at home so all he really did was shoot some of my reloads and there's a distinct uncertainty factor in play. He might get into it big time, in which case I'm happy to swap presses and let him have the Dillon. He might just load occasionally, in which case a single stage or turret press is all he really needs.
Or he might try it and forget about the whole thing. Or start little by little when he has a chance to do it on his own. That's really up to him.
I really wish the prices were even close to what they're in the US. RCBS Rock Chucker master kit sells for close to €600 / $700, Lee Challenger kit for €215 / $250 (on sale right now, regular price €279) and everything worth considering somewhere in between.