Don't know what an AT adapter runs to get that one to work but I'd imagine you could use that as a bargaining chip
Usually it's just a few dollars for an AT-to-PS/2 adapter, then you can use any PS/2 port or (most) any PS/2-to-usb adapter. I prefer the ID innovations ones, but they are like $15.
So it's not THAT expensive. I have AT to PS/2 adapters (as well as the much less useful other way) that I'm not even using.