How bad is the damage? If you can repair the bumper go that route. If there's a dent remove the bumper and use a heat gun to make the rubber more pliable. Use a large screwdriver or pry bar to get it to pop out from the back. If theres' a rip or tear in it, use a grinder to mend it. The friction causes heat which will actually fuse the rubber back together. Then it's time to use plastic. Metal glaze works good on rubber. Regular bondo or something similar doesn't adhere to the bumper nearly as good. Sand it smooth and use a primer suitable for rubber and plastic parts. Marhyde has a good primer with a flex agent which I always use. It's in a red can, and it's called flexible primer. Wet sand it with 600 grit after applying a few coats. It sprays very thin so watch out for runs. After it's smooth wet sand the entire bumper with 1000 or 1500 to knock down the clear. Spray the spot you fixed with a couple of coats of base coat, let it dry, and clear it. Wet sand the bumper with 2000 the next day, buff and polish, and you're done. That concludes your lesson on bodywork 101.
Oh, yeah, if you don't have any of these tools/supplies buying them will exceed the price of ten bumpers. So I'd opt for the .99 cent sticker, but make sure it says something in ENGLISH PLEASE!!!
