Buy new rob, they are cheap.enough, they come factory painted to match your car colour code,
The arch extensions have self.adhesive strip on the inside that only come with the new subaru genuine part so dont buy a spurious part, a secondhand on will have damaged clips or adhesive strip will be gone.
I got mine from.import car parts, about 180 to 200 euro total for a set I.e. left and right hand sides very reasonable