lol, Silver is NOT common, its the hardest of ll the colors to find anything but junk.
The proper way to get a commercial bumper done is lots of prep smoothing the finish and paint prep, work and additives, and then it will possibly last, the cheap way is just thick filler primer on the textured finish and it may last a couple of years if youre lucky.
The problem is 2 fold, firstly its VW secondly its a Transporter, so almost everything is overpriced junk on ebay which for any other make would be worthless, but you can thank too many starry eyed fools paying too much for this privilege.
Most painted commercial bumpers on ebay fall into the badly prepped and failing junk category, the remainder are knackered caravelle items.