I think that your heart is in the right place but a gift is meant to be just that, a gift. Not a lesson. And yes, a gift does mean than something "will just be handed to them." You don't have to "earn" your gifts, do you? At this age, your message will most likely fall on deaf ears anyway. If I were you, would get a gift for "now" - gift card to a store they like (or the mall), an iTunes card, cash, etc.
And if you want to pique some financial interest, also buy a small amount of stock in a company that would be of interest to them - Nintendo or Sony (video game companies), a beverage company, car company, etc. - and then use that to show them how the stock market works and then you can use those conversations (not during the holidays, later) to work in some information about saving and investing, etc. Oneshare.com is a great place to buy single stock shares, you can put it in the recipient's name, get a certificate to frame the share, etc.