I had the same issue a couple weeks ago. I googled "how to tell fake Louboutins" and came up with a bunch of websites. Several have known sites for reproductions. I posted a couple below, but if you google it you will find tons. From what I gathered in my reading though, if you find a new season Louboutin for like $300, it's not real. One site I read said a customer emailed asking if the shoes were reproductions or authentic, and the site wrote back saying the were very "high quality" reproductions.
Spot the Fake Louboutins! | Luxaholics
Don't Fall for Fake Louboutins