Where to purchase window tint for DIY

I am looking to tint my trusty 2010, but it seems that you can’t just outright purchase rolls of name-brand tint very easily. 3M, Llumar… they all require you to be an installer to make a purchase.

I know this is probably a long shot, but does anyone have a good connection with a tinter/company that would sell me a roll of the good stuff? My brain won’t allow me to pay for something if I know can do it myself, and I’ve been known to spend more than it costs just to be able to DIY something.

The tint on Amazon and walmart is garbage, and the listings on eBay are not guaranteed authentic, and from what I’m told, they are not authentic.

This is frustrating and I don’t understand it, but if you know anyone who can help me, please reply. Thanks!