Meguiars scratch-x can be used on plastics and it's awesome stuff, as is there entire range for that matter. Check the booklet to make sure it can be used on clear plastics as I've never tried it on clear, but it does a fantastic job on anything else, including removing scratches from my side windows.
I polished off overspray on the screen of my motorbike with Autosol metal polish, it didn't scratch the screen at all.
I have also used toothpaste on plastic watch faces for removing scratches, it takes a long time!
The small kit at teh top of this page will be more than adequate. I've used it several times when machining things from clear acrylic, you can get rid of any tool marks and end up with a glass clear surface.