Mystery Football Kits?

Hi. I've seen these websites everywhere lately. As a client you go there and you order a mystery football kit. You probably receive what they didn't manage to sell or something.

Anyone knows how you can set up a site like that? Everything seems to be legit so they probably have licenses to sell and everything.

How do I get my hands on those shirts and licenses and everything to run a website like that? Please and thanks.

Nobody?