Wow, awoke an old thread!
Tint varies by what product you choose. It could be anywhere from $200 up to over $1,000. It also depends what you have tinted. Just the side windows and back? Windshield? Pano?
I had 3M Color Stable 30 on windows and back in my first Model S, I believe the cost was around $250. On my second Model S, I decided to upgrade to 3M Crystalline for its superior heat blocking, and I decided to include the windshield as well. I think it was around $800.
The good news is that there are a lot of choices out there!