I compared a new oem vw cap I bought from local dealers (£8.50) with the 4 Ebay "oem spec" (£10 for all 4), that I purchased recently.
Tbh there is very little difference between them to the untrained eye. The individually bagged and sealed Ebay caps were covered in blue protective film, the alloy logos were nice and shiney and correctly raised, and even had the same rough-feel black plastic indents inbetween the logo. Only differences between them was the country of origin and batch info layout on the back and very very small differences with regards to the space between vw lettering on the logo. They even weighed the same!!. Very good copies if I may say so!!
lets see how long they last tho......
Ebay seller;
http://www.ebay.co.uk/itm/200923324347?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649