Tisunac,
3M is the largest supplier of automotive cleaning and polishing supplies. Meguiars runs a close second. Mothers is in there too. But, in your local auto parts store are shelves and shelves of all these products. Most auto parts stores won't carry the 3M products for this 'cause, they're normally sold at specialty stores and supply outlets for detailers.
Now, as for your plastic, Well Sir, don't expect anything more than a bee strike or bird droppings to simply "buff out". Ain't gonna happen. Plastic is PLASTIC! When scratched, it's DEEP. Plastic is weaker than paint. What would potentially scratch paint, most likely would actually damage plastic. And damage cannot be undone. Paint, in many cases, if it's deep enough, can be buffed out and blended in. But, damaged plastic goes deeper than paint.
Oh, yes, you can work at it and you can make damage and deeper scratches look a bit better but, you'll never get rid of them. Take for instance, the rear fender on my 2007 Yamaha TW200 I just purchased. It was layed down on the right side and damaged the plastic (and a few other things). There is no way on this planet that those are gonna disappear, with ANY amount of work and or product. NEW PLASTIC is the order of the day here. Good luck.
Scott