I'd have to say my HP-2000 systems that are running are the rarest that I'm aware
of. I know of a few folks who have various bits and pieces towards assembling one, but not
complete. I know two collectors who (each) have most if not all of the parts, but the
systems are far from operational and likely never will be.
So I fairly strongly suspect that my running HP-2000's are the only ones left,
anywhere. I have one HP-2000/Access system using dual 2100A/S cpus with HP paper tape
readers and punches, another HP-2000/Access system using dual 21MX/E's, and an
HP-2000/E using one 21MX. Each of those have their own 7900, 7906 disc drives and 7970
(not the 2000/E) tape units.
I think the most I ever paid for a system at once was $1500 for a "system", and
about $2000 for a pallet of two incomplete systems. But in order to get the 3 HP-2000
systems mentioned above and running, I'm sure it's edged uncomfortably into the 5
digit range.
All the other systems in my collection, while perhaps highly sought after... there are
tens if not hundreds of identical systems in other collectors hands.
J