It depends on the film. This weekend I dropped $500 to have my car tinted with Huper Optik at Song's Tint Masters. They did a good job. It's better to pay more for a good job then have some dude hack up your car for cheap. The starting price at Song's depending on the film was $120 for 5 windows on to $500 for Huper Optik.
I can't tell you how important it is to choose a reputable place. These guys can tear up your leather, cut your rubber molding, burn things with the heatgun, and just mess your car up. Many people recommend Song's so I went there and I am satisfied. With the Huper Optik film, there are bubbles that started forming today but they will go away as the film dries in 2 weeks.