Cameron -
With any high end tint, you should be fine with 50% on the front passenger windows. I had never thought of using the gradient (30-40-50) until the guys at Lightspeed showed me a car with it. I had the same issues with wanting to have tinted car that looked nice, but didn't want to mess with the law.
For Huper Optik and Coupe, all windows, it'll probably run you around $400 at any reputable place. Be sure to ask for custom edging to the tint looks like its factory finish and doesn't have a border/edge - usually about $40 more for coupe.
Here's a picture of my buddie's G35 right after getting same tint as I did in the 30-40-50, and also blue. You can see my car behind his before getting tinted. I forgot to mention they also give multi-car discounts as well, so if you have a buddy that's thinking of getting tint job done, you should bring them along.
Notice, with the sun behind it, you can see pretty clearly through the front passenger windows, and it looks more like factory tint.
-Stink