If you don't have a nav antenna or satellite receiver antenna that needs to see through the tint, I'd go for llumar titanium metallic tinted to the legal limit (which isn't all that dark). For that tint and most that aren't ceramic, I've been to Westside Glass Tinting. It's on Old Katy Road between Jeff Haas and the beltway - it's in a ****** looking strip center, but the guy does good work. I paid about 120 for a sports car there, and 150 for a large sedan in that tint.
Other than Westside GT, I had my current car done with Huper Optik Ceramic 20% at Executive Motorsports over near the galleria off of Richmond. I only used the ceramic because I tested a piece of the Llumar metallic and it blocked the signal to the nav. The ceramic also works VERY well, but it's freaking expensive (at least twice as high as metallic). When I did the ceramic I think I came out at 400 after tax.
Whatever you do, don't get dyed films - they'll look like **** in 5 years.
I'll expound on my tint selections above a bit more: If you go with ceramic or metallic over dyed, you reflect more IR radiation (heat), while not having to go quite as dark. Metallic does cause some interference issues, but for most applications its fine. I also found that most installers (I hung around on some tint installers boards as well as called around) like llumar and wouldn't put 3M on their own cars.
Oh, and the llumar I mentioned above I believe was 28% on the sides and 18% on the back glass (percentage is transmission of visible light - or how dark it is - lower #, darker).
I'd also check out some of their work before you schedule an appointment. You dont want a bunch of seams in the rear glass piece (to accomodate the curve of the glass), bubbles, rough edges, etc.
And for most of these places, it's not like the supermarket - prices are very negotiable. I've had installers knock $40 off a job - it all depends on how busy they are.