for what it's worth, there are kit computers you can buy still. It's a niche market, but there are a good few z80 kits out there and ben eater sells a kit for building a custom 8bit CPU on a breadboard and a 6502 based kit
I think they still make the Z80? In my uni it was an 8088 in minimal mode. At work we have a few JK Nd:YAG lasers running on 6809's still making money.
