if painted bumpers is what you are after, I would suggest getting good cores from someone and sanding them with 60 or 80 grit (use a power sander if you have it), then hit them with self-etching primer, some filler primer, sand them and paint them.
I painted my bumpers 20 years ago and they help up just fine. I did the front again, and a decent rear core, 2 years ago with spray bomb primers and they held up just fine.
Like anything paint related, it is all in the prep.
Jason