What would be the least expensive N8VEM SBC possible? 

To make this interesting and so that builders with enormous amounts of spare parts lying about can’t “cheat” by digging through the junk box let’s assume all parts must be purchased from a vendor.  The vendor should have a price that’s published.

Likewise, “fully functional” is a system that boots CP/M and communicates over the serial terminal but doesn’t have to do anything else.  Most of the on board peripherals are not really necessary and can be safely eliminated.  It makes for a less interesting SBC but certainly reduces cost significantly.

Also to make this interesting it does not have to include a serial cable but does have to come to a interface of some sort. In other words, if you hard wire the serial cable to the UART, you still need to include the whole cable including the DE-9 connector.  Alternatively, you could leave off the cable and DE-9 and just leave a dual row header instead.

Construction techniques are definitely a source of cost.  Using sockets of any kind can be eliminated.  Of course, I would never recommend it but I know Juha didn’t use sockets and his system worked great.  Desoldering that PCB must have been fun though (not!)

What else can be removed or substituted?

Actually this thought experiment may be useful for those interested in using the N8VEM SBC for educational purposes.

Thanks and have a nice day!

Andrew Lynch