I think these are A4988 based and equivalents are widely available, for example:

https://www.pololu.com/product/1182

or

https://thepihut.com/products/a4988-...-black-edition

There are also nearly identical boards with more recent driver chips such as the DRV8825:

https://www.pololu.com/product/2133

...and I have bought those from UK stockists.