I know some of them have gotten old, but most look unique and apart from a few ninjas like gai and rock lee, I have yet to see two ninjas with same costume. Since they are training all the time, where would they get time to have those made?
At the "I am Ninja! Ninja! Ninja!" store. They sell a lot of items that only ninjas with names can purchase. They secret pay Naruto for creating their name.