I now have four metal mangling machines that need the venerable ISA slot to
operate... These computers are not available new anymore and the new parts
route is about gone too.

I'm settling around one motherboard, CPU, memory, video card combination.
Makes it much easier to maintain. I can do an entire computer swap in
minutes if trouble happens. Or test one component at a time in a spare test
computer.

lets say I'd like to run these machines another 20 years. How many spares am
I likely to need? I'd like to buy them up now. (Note: I don't think I need
to do hard and floppy drives yet - still a lot of these around)

Karl