This is an old post, preserved for reference.
The products and services mentioned within are no longer available.
Updated versions of the Minstrel 2, 3 and 4th are now available from The Future Was 8 bit.
These are now single boards, with the keyboard integrated into the main board. The is a keyboard overlay PCB with keywords as appropriate for the system, and the optional ZXpand board which is soldered onto the edge connector.
The Minstrel 4th is 'designed for RC2014' and can be expanded via an RC2014 bus connector, to make use of all sorts of existing expansion cards.
All of those kits are available now from the new 'Tynemouth Software DIY Computer kits' section of The Future Was 8 bit - https://www.thefuturewas8bit.com/shop/tynemouth-products.html
Along with the Mini PET of course.
2022 Update: Some of these kits, along with the updated version of the The Mini PET are still available from The Future Was 8 bit.