Several things to pass along to the lad.
First buy what you like, not simply in an effort to make an investment. (if you are simply looking to turn knives into an investment, buy Randall, Case and other "blue chip" knives and place them in the safe, only handle them when you oil them... Now that sounds fun)
Go to shows, meet the makers and purveyors and get to know them, you will meet great people and learn a ton about knives.
Get the lad a subscription to Blade, Knives Illustrated or Tactical Knives
If you think he has the bug, buy him the best knife you can for gifts, subject to your budget and the event itself. I try to buy each son a knife for Christmas, birthday, etc..... and went a little crazy for my son's 18th birthday. That said because the maker has become a good friend, he both cut me a deal on the price and upgraded the scales as he gift to the lad.
If you do buy a valuable or very collectable knife, don't take it on a camping trip. For example I have a Randall Md. 1 which is a total safe queen, but given the cost, that is it's lot in life... Because the design of the knife is fantastic, I picked up a copy of the same by Blackjack and use it all the time. While the Blackjack is a nice collectable knife it's worth about 25% of the Randall.