If you go to a shop like Gerrell's Hockey World or Duffy's Hockey and Sports (or any "real" hockey store) they will be able to sell you any variety of good options. For a 10 year old, there is no need for the most expensive helmet around. Like the other poster said, a good fit including the cage is most important. Talk to the salesmen and have them help you fit the helmet. I personally am a fan of Bauer helmets. Their 1500 is what most young kids wear, but the 4500 would also be an option. Most helmets like those are sold as combos, that is they come with a cage. Good luck and make sure your son has fun playing hockey!!
http://www.bauer.com/gear/player/helmetsfacial