I have just picked up a clean looking pair of HD580s for £74 on eBay from a guy in Germany. They never seemed to come up in the UK and when they do they go for silly money because folks know they are so like the HD600 and HD650 which go for even crazier money used
Figured I'd fine more used HD580s in Europe with Sennheiser being German, and sure enough I did.
HD600 grills are on order for £20 and I noticed that a pair of HD650 drivers are only £80, which is actually cheaper that the HD600 ones.
Can't wait to get hold of them!