It doesn't look quite like an M2 either... If you look closely, you'll see a notch at the upper left corner that's a little bigger than the Esc key. That was IBM's next case design after the M2. (They thought that making it slightly asymmetrical looked more modern.)
You can also clearly see it has Windows keys, which no IBM keyboards had till
after the M2. (IBM was the last holdout on those, as they still wanted people to use their own OS's rather than Microsoft's.)
That said, IBM's RD keyboards from this period (KB-7953, KB-8923... are there more?) are quite decent. They're sturdily made, with metal backplates and a nice definite touch. Some people have
compared them to Topres, but that may be a bit of a stretch. They're certainly several notches above the typical cheapo RD board. Plus, they say
IBM (woo!).
I
might pay $30 for a NIB KB-7953, but certainly not for a used one. If you're interested, I'd offer $15 and let them raise it to $20. I think it'd be worth that if it's in the like-new condition they say it is.