Beware of non-OEM wheels. I bought a set of Prets for £800. brand new and 2 of them were slightly buckled.....they were replaced but lesson learned.
I had a set of new rep wheels before also 1 cracked 1 buckled both within 6 months never again OEM only for me.
IMHO it can largely depend on who the manufacturers of the aftermarket alloys are. Companies such as BBS, Borbet and Ronal have an extensive range of aftermarket alloys. They also make many of the OEM alloys for VW so I’d have no hesitation in buying a set of aftermarket alloys from one of those manufacturers. There are other reputable aftermarket alloy wheel manufacturers too.
As with any purchase, it pays to do your research and with alloys I’d want to know who the manufacturer is and ensure their alloys are TUV, ABE, JWL (or similar) certified, so will have gone through thorough quality and structural safety testing procedures.
OEM alloys can also have their problems - e.g. there’ve been quite a few instances reported on forums of genuine OEM VW 19” Pretoria alloys being susceptible to cracking and buckling.