I looked to see if they was still produced, but nope and a second hand one is from £70 up to £200, crazy. I have found some G500s mice, which looks ok and almost the same as mine, but with a better sensor, but again this have been discontinued and the chepest is around £41 and either from Chine or the U.S.A.
The one that took the place of that one is the G502 Proteus Core. The 502 looks strange, it do not look like a normal mouse, but the reviews are pretty good.
I wish they would keep to designs that work instead of mucking about with things.
Desktop machine now powered by windows 8 pro 64bit, no dreaded metro and Linux , laptop by Linux