As above really, just wondering price, what it's made of and how to attach?

http://www.perfectpanels.co.uk/index_catalogues.htm

HCP Part Number: 91-32-608

Go into: all parts

VW

polo 81-90

then towards the bottom 91-32-608

I had a feeling this was gonna be about squareback arch trims. As far as I'm aware nobody has them on here.

if they are the plastic ones they would be great for my new polo mk3 got damage on one of the rear arches this would cover it up perfectly. think mk2 and 3 rear arches are the same on the hatchback version

They are, but I think where the rear arches meet the bumper might be different.