Just purchased an Instrutech Hornet Ion Vacuum Gauge. ~$900.
I chose to buy this to have a simple gross pressure gauge so we can begin pulling a vacuum. Sort of a sanity check. We expect the gauge to work. Without a proper gauge we are lost.
The hornet is the most simple/user friendly of the gauges I’ve explored. All in one unit, just plug it in and go. I think that’s the first major hardware I’ve purchased new!
Just waiting for nuts and bolts (literally) and some conflat gaskets to arrive, then we can pull first vacuum.
Prometheus Fusion Perfection 
I have it from a very reliable source that you will need to get down to 1E-6 torr before applying high voltage. Otherwise things get “exciting”.
Also the MRI magnets require LHe cooling. May I suggest a talk with the mfg or a copy of the manual before getting the MRI. The field possible with LN2 may be rather limited.
re: 1E-6 torr, even for a fusor?
re: MRI: tried to get some info from philips, still looking for the right person. I realize it requires LHe cooling. Still worth checking out.
I would want a plan of attack with a reasonable chance at success before doing something like this. It would incur big shipping and storage fees (can’t fit that thing in my current space). The magnets are likely encased in epoxy, which would need to be dissolved (if possible). Pretty major industrial undertaking.