Managed to find it on eBay on the cheap! A local seller as well.
I'd love to have a go at some homebrew, but I think the best way to do that is with an emulator. If I wanted to work on the Yaroze I'd need to jury rig a special serial cable. Also the Yaroze only has 2mb memory, not the 8mb of a dev console, so you can't compile with debug symbols 🙂
However, there is the small matter of me not really knowing C. Well, not well enough to know what I'm doing, anyway. But perhaps this could be a good hobby project for getting my head around C?