1. Bought on eBay. E5-1620 V3 CPU, 256GB SSD, NVS 310 video card. Certified refurbished, 1-yr hardware warranty. Just right for trading.
2. Old workstations? They are Dell T3500s. Dell didn't produce W10 drivers for this model, though I hear you can get W10 onto them if you start with W7-64bit and upgrade to W10. Don't know what that does with the drivers, however.
They will be good running W7 for quite a while... especially the ones not exposed to the net much (still good for off-line gaming and office suite functions). I might sell a couple of them cheap... might just donate them to a local Veterans group, I dunno.
How many workstations do you have running at one time?