I had one of these IBM beige mice, here's a picture taken from Kishy's site:
I was wondering the different models of them, which is the best, and so forth. I do know there are the darker grey button variations.
I used one like Kishy has above, and, here's the story behind it. It worked for a good few years, but then it developed a problem of randomly make the cursor jump everywhere chaotically. The strange thing is, the mouse would work for awhile, but after a few hours malfunction. I got mad and then proceeded to smash it, and threw it out. I wish I would have kept it to analyize...
Anyways, it would be great to get another one of these. I found them very easy to use; and I like how the IBM logo was engraved in.
I'm not sure the timeline of when IBM made these mice; I say mine was in '97 because that's how old the computer which came with it was.
EDIT: I also like them as a mechanical mouse. I'd still be using mine IF it didn't break. I hate changing equipment when it performs its job well.