Like if you go on tumblr and search hipster, stuff like that.
There a number of reasons that hipster fashion is not easy to copy. Self-identity is heavily tied into what being a hipster is all about, however you will seldom find a hipster who accepts this title readily. Secondly, hipster trends tend to change quickly, and third when that trend is copied by others those in this life-style find new ways to express themselves. Lastly, more than one type of hipster exists with a different lifestyles and clothing choices.
I'd say the thrift shop. Since "hipsters" don't really follow trends in fashions I'd imagine that you can wear pretty much anything as long as you have unkempt hair and huge 80's glasses.
I have a friend who has a somewhat hipster style(: she shops at forever 21, and urban outfitters, look up there sites.