Their kinda right, back 2 black etc leaves a coating which can be an arse, but shouldnt cause major probs if done properly. £100 a bumper to be honest isnt too badgoing by prices today but you could prob find somewhere cheaper.

Would baiscally need a thorough clean using something like thinners (we use it to clean any resin residue on the SLR panels/shells) then plastic priming and painting, etch isnt really any good for plastic as its main use is to 'grip' to bare metal and offer a rust resistant coating, althou have used it as a wet on wet primer before now, it just doesnt have much build to it, so chances are will easily stone chip aswell!