That's pretty much what Photosync will cost, yep. Offer cash and see if you can at least save the sales tax.
And the windshield is definitely worth getting done with Photosync 75. The heat reduction (50%) is nice, but the glare reduction is particularly noticeable.
I regret not getting the front pano panel done, but there's time yet before travel starts again next month. My low-tech solution is a baseball cap.
Yes, windshield tint is subject to laws in your particular geopolitical designation.
Yes, paying cash shouldn't matter, and yet go figure, sometimes it does.
Yes, there are pano screens (see Tesla Accessories at the TM site); sadly, they don't work worth a tinker's damn except perhaps as a bug deterrent.
And finally, if you search for this subject, you'll find more than a few points of reference from numerous states.
Added: Oh, and the reason it's worth considering the high end films is because you get superior performance with a lighter tint. That's why the majority of Teslas that have Photosync will have 35, else 45. With 75 on the windshield for those that get the windshield done since it is just about invisible.