Well we bought the cheapie one from Harbor Freight (if you have one near you). After coupon it was 9 bucks. It REALLY did a FANTASTIC job. I restored both lens covers on my coach and personal vehicle. Mine were "yellow/brown" and dingy. After restoration they looked nearly new.
4 whopping cylinders on Toyota RV's. Talk about great getting good MPG. Also I have a very light foot on the pedal. I followed some MPG advice on Livingpress.com and I now get 22 MPG! Not bad for a home on wheels.
A single sheet of 2000 wet/dry sandpaper will give you the same results and let you keep money in your pocket. I have been doing it for years in AZ and FL with remarkable results. A squirt of Aerospace protectant will finish of the job for years of clean lenses.
The 3M kit is $10+ cheaper. Don't know whats in the Meguires, but the 3M works perfectly.
And NO, a single 2000 grit sandpaper wont do the same thing. You can't clear polish a lens with sandpaper, wet or dry. Nor will just rubbing compound remove the layers of dried and crystallized plastic. THAT needs a real abrasive.