My headlights are rather dull/yellowish-
Ive seen many ads for sanding your acryllic lamps clean but am loath to do so- or if it does need doing- whats the best product/method or should I just go out and but new headlights?

 

I used a 3M product and did it my self and I did notice a difference.
3M Headlight Lens Restoration System

I also have a CLK 320 and my light were dull. If you do get this product I would suggest doing it by hand instead of using the cordless drill. The attachment can be manualy handled and I found it to be a bit easier. Check out lens cleaning tips on youtube lots of good tips. Then go for it.