there are companies that sell thick plastic self-stick clear protection for headlights, Griots Garage is one. They are really my competition (although I doubt if they know I exist, only one of their excellent catalog mailings costs more than my entire budget for a year or two or three!) but I buy stuff from them because I don't WANT a business that big!
I bought the headlight protection from them right after I got my 300C, and tried to put them on and had zero luck. Followed the directions perfect, but they looked terrible.
Be careful putting wax on the headlights, some products can yellow them. But worse is to keep cleaning them and adding scratches. The worst examples are about every Dodge/Plymouth Neon ever made after a few years. Those cars must have very soft plastic.
Meguiars clear plastic polish works very well. Don't rub hard, just light pressure.
I have used Rain-X with good results to help prevent bugs from sticking and make cleaning easier. You have to apply it about once a week though, or every time you clean the lights.
BE careful using plastic headlight "kits". Most of these are for the type of lights in the Neon example that are already quite bad. Using them on lenses that are in good shape can speed up the aging process.
From what I can see the 300 uses high quality headlight material, just be careful when cleaning them.