They're from a company called SKXMODS, and they're based in the US.
Here's a link to their page for AE-1200/1300 mods....the cases alone start at around $100, so not cheap, but certainly seem to be excellent quality.
I have three Casio Royals, and have drooled over these for some time, but they're just a bit too pricey for me to justify that cost on a £30 watch.
I have a couple of Chinese made knock-offs, which are not great quality - the module moves when the buttons are pushed, and can be hit-n-miss whether they activate the desired function.
But, they did only cost a tenner each!
Maybe one day I'll get a proper one from SKXMODS!
@Arnold Grove
Just as a matter of interest, what was the shipping time (and cost if you don't mind my asking) from the US, and were there any customs issues etc.?