Where can I find a real Florida Gators Tim Tebow #15 jersey with Tebow across the back?

I heard that these jerseys are rare and can only be bought out of the university. I would like one really bad but I dont know where I can find the real thing. I've seen alot of the #15 jerseys but they don't have Tebow written on the back. Does anyone know where to find these. Thanks if you can help.