are you interested in cosplay? why not try some costumes to make your teenage fashionable .you nust be amazing.here are some cute goods, you can have a look, i am sure you will love it. http://www.worldwidecosplay.com
It really depends on gender and what he/she likes. If it's a guy then I'd recommend checking out http://etthreads.storenvy.com They've got some pretty cool hoodies and little gadgets that most guys would think are cool and enjoy. Good Luck!
What are you interested in? if you want to buy the sports jersey, I know one. the service is good, and the price is also low. I have bought two jerseys for my little brother who is 16. www.maryjersey.com It arrived on time.