Wow, I didn't expect such a big response. :D haha
As for production of PCB's, I did use PCBWay as they are a sponsor of my Youtube channel, however, they are a slightly more 'premium' Chinese manufacturer.
Using JLCPCB or Seeed Studio (with 3 e's) will be cheaper and still have very good quality.
Gold plating is a good idea for the Main PCB, and a manufacturer that can chamfer the card edge connector is a good idea too. JLCPCB and PCBWay can do this (it's a minimal extra cost per PCB) but I think Seeed Studio couldn't last time I checked.
I have used JLCPCB extensively in the past, their prices and quality are quite good.
I'm not quite in a position to run a group buy myself as I live in Japan, so shipping and logistics would be more expensive and difficult than if someone in the USA did it instead. However, I am more than happy to provide 'technical support'.
Just let me performance check my unit first to make sure I have it all working 100%, I'm a bit paranoid that I might have a gremlin hiding somewhere. :D haha
Anyway, I'm glad you all like it. I have a few more ideas for some similar projects in the future so stay tuned. :)