Here are some links to some single-board computer kits using the Z80 CPU that I have found.
The RC2014 is a SBC kit built with a backplane so that numerous modules are available to expand it. Firstly, the RC2014 Classic II kit (around £76) contains 5 modules (CPU, ROM, RAM, Serial I/O and Clock/Reset) all connected separately to a backplate. The RC2014 Mini kit (around £64) combines all of these modules onto the same board to make things easier to assemble.
Alternatively, the SC114 is a simpler kit that is compatible with RC2014 expansion modules. It is also cheaper – around £29 including all of the parts needed.
The LiNC80 SBC1 is more sophisticated, being able to run CP/M without needing any additional modules. It uses an alternative expansion format, the Z50Bus which is different to the RC2014 bus. It costs around £107.
The SC118 is another simple kit, similar to the SC114 but is designed to be compatible with the Z50Bus. It costs around £36.
These kits are fairly simple – as standard they won’t connect to a display and will only really let you connect via a USB cable to your PC. If you want something more advanced, you can buy kits that mimic home computers from the 80’s.
Please let me know in the comments if I’ve missed any!
Image Credits: Twylo