Consider a set of V-Drums by Roland..He can practice with headphones and plug into an amp for jammin out.
The best of both worlds.
Blasphemy!!!!!They are loud, though. That's why they keep me in a cage
But then again, he might end up playing with a Rastafarian steel pan band.....
Or on a good note, he might be the next Mike Portnoy.[/size]
In any case, to keep the noise and cost down, get him a snare drum to start. If he doesn't get board learning the rudiments and sticks with it (pun intended), you will know that he is serious.
Drums are not cheap. Getting him a cheap set will only discourage him (as with any cheap instrument). A good kit could run into the 1,000's of dollars. Cymbals even more so. I have a ride cymbal that cost me almost $400. The others average about $200 a piece. A good chunk of change to lay down for something that you beat upon incessantly with a wooden stick.
Cheap drums will not keep in tune, and the hardware will fail. Cheap cymbals will crack and even break on occasion. I play a 20 year old Pearl kit with about 8 Zildjian cymbals. I have practiced for countless hours upon it, schlepped it to many clubs for innumerable gigs, and haven't broken a head or cymbal in 15 years.
Music is a wonderful gift to have, and share with others. I say encourage it, but make it clear that for the expenditure on your part, there must be some commitment on HIS part.