Fortunately, my Lib came with them, but they do make a huge difference when you drive, even with stock bulbs. The fog plus healdights are brighter then my brights when looking down at the road but the brights by themselves shine higher and further like they are supppose to do. Often, when i drive with them at night I usually get flashed it's s annoying, but most of the time I leave them off. What is even more annoying are those pricks that drive with HID's. Like it's ok that you blind and annoy everyone else on the road but you should have special treatment. So I just leave the fog lights on for them becasue there special LOL!
Sorry couldn't tell you what it would cost :[