The only rarity with these is the label on the machine. There are a handful of collectors worldwide who specifically collect WGS machines. I am friends with one. He will sometimes pay (in my opinion) extraordinarily large amounts for a machine he needs just because he’s trying to own each of them.
He already has one of these so he won’t be one of your customers. The G3 beige servers are often on eBay and other platforms and their value seems lower then other WGS models.
I think the WGS95 is one of the most desirable (providing it has the elusive PDS card), along with the WGS 9150 (which has a unique case). Other honorable mentions for desirability are the WGS60 machines, which seem to be in lower population than most others.