i live in canada and theres a place called Canadian Tire. its like a homedepot but its got a automotive center and lots of auto parts. i saw it there. they had a 3m kit which came with a mandrel and a bunch of discs. some sanding and a polishing disc.
homedepot should have it.
i used the fine disc. when i was doing this, it was winter and very cold outside so i was doing it quick and applying lots of pressure. if you take your time and not apply as much pressure, i'm sure it wouldnt leave many scratches.