ebay.co.uk: New IBM M4-1 for ten pounds

[ed_avis]

This is 'buckling rubber sleeve' as IBM calls it, in other words rubber dome, with a Trackpoint in the middle.  It is strictly speaking a "Model M" though not as we know it.  For ten pounds you can't go wrong: http://www.ebay.co.uk/itm/361811486248

[ed_avis]

The same seller also has a splendidly ugly mouse, even by IBM standards: http://www.ebay.co.uk/itm/361811491518

[menuhin]

In my opinion the IBM M4 is a collector item for IBM and keyboard enthusiasts, but not a nice keyboard to type on (for me).

There are nice rubber dome keyboards that feel (almost) as good at the Topre and some lubed MX switches. I tried on an M4 and categorized it as a bad rubber dome keyboard.
Otherwise, it looks real great.

Edit: I missed my rubber dome IBM 8923 (perhaps one of the best rubber dome keyboards, see forum posts about the "KB 8923")

[ed_avis]

Yes, it's more of an IBM collector's item than a practical keyboard (even though I have certainly used one to get work done).  The Trackpoint is nice in theory, and probably worked pretty well on a 640x480 screen, but it is awkward to drag the pointer around on larger desktops.