Just had my truck done here in Austin and it was $195.
The "purple" tint is tinted with coloring, and it fades after about 5 years in the Texas sun, causing it to turn purple.
The more "expensive" tint is tinted with little flakes of metal. Metal doesn't fade, so it will last a long time. NEVER clean the windows with ammonia, it'll ruin any tint job over time.
I've had my MINI tinted for 6+ years now with no fading.
Usually, the price difference in materials is only $20-30, the cost is in the labor. $400 is outrageous if it wasn't a dealer add-on.
Make sure to keep it legal darkness. Some shops might offer to tint it darker than the law allows, but I wouldn't recommend it. (Especially if you live in a big city like Houston or Dallas). http://www.tintlaws.com/laws/TX/
Once you get the tint done, get a front window shade and USE it. Pony up the extra $3 for one of the reflective ones, it'll save your dash and make a huge difference inside the car.
Welcome to Texas!
-Rob