There are basically three kinds of window tint film.
Dyed - fades soonest
Metallic pigment - lasts longer, fades to reflective, can interfere with GPS/Sat radio
Ceramic - longest life, most expensive
Had the cabrio done for $100 in Delaware at Forumula 1 Tinting and Graphics, who have done two now:
1) Window Tinting
1) Window Tinting
You can tint the front windows beyond the standard legal limit if you have a medical waiver (opthamological, dermatological, etc.).