Alternative switching system of Keithley7001 mainframe/7012 switch matrix?

[hank780420]

Hi:

I have a home built measurement system equipped with Keithley 7001/7012-S combination to perform DC/low frequency AC measurements.
However, Tektronix told me that they stopped providing maintanance to 7001/7012-S when I found one of the 7012-S card became unrecognizable to 7001 several month ago.
I did get two 7012-S cards from e-bay with relatively resonable price, and with good luck, they both work in good condition.
However, I notice that it becomes harder and harder to find switch card for 7001 mainframe, I'm worry that I can't find any replacement in near future.
Also, I won't consider the "awesome DAQ solution" from Tektronix as they force you to pay adittional $1000+ for a barely useless 6.5 digit DMM for a simple switch system.
(That is DAQ 65XX series)
I do consider Rigol as their products are siginificantly cheaper, but I'm in doubt with their equipment reliability.
As I'm doing materials characterization in academic which involve a lot of low-level voltage/current measurement, I only give my trust to equipments from Keithley and HP/Agilent/Keysight.
My experiments often require multiple instruments and DUT pins to be switched with high flexibility, e.g. Van der Pauw method, which requires to exchange voltage/current pins, differential configuration of 7012 card really helps.
 
Is there any suggeted replacement to Keithley7001/7012 combination with reasonable price and adequate performance?

[dietert1]

Recently we got a Keithley 3706 and a 3720 multiplexer (60x latching relays).
Although it already has 15 years, it's like new and a nice instrument. It includes a 7.5 digit DMM with a large VFD display. Backplane and switching modules support multiple analog busses. Lots of computing power inside with Win CE and LUA script programming. With its six bays it provides up to 500 channels or so. The 3706A is a current model with improved firmware.
I worked a bit on the backplane, soldering some of the press-fit socket pins. Also i moved the DMM analog bus to
low thermal EMF binding posts on the front. Yesterday i wrapped the wiring adapter to protect it from air draft. Now, while scanning in the 100 mV range the channel zero is stable with 7 nV standard deviation. Impressive.

Regards, Dieter