I dont have a lot of room to say much being a college student myself (thus not far away from my teen years), but something like that doesnt seem too bad. Maybe have him sell some of his other clothes to make money for more of the stuff he likes. You have to give a little and let them express themselves. Not saying they should look too extreme but...letting them indulge in some fads wont hurt them. Theyre only young once and in high school they dont need to work (usually). Let them get it out of their systems since they can look pretty much how they want at this point. I wish I had died my hair more in high school since now my job(s) require only natural hair colors. They have plenty of time later to dress nicer, have short hair, and to be an adult.