The only open design I've "seen" in the last decade or so using memory buses
Yep, not very common these days. Still built or not the design will still be open source FWIW.
a website for sponsoring his project to get it started
Yes I remember that now, kickstarter.com
it's called, I'll have a poke around.
But I checked out the midi board they are making, it seems way more complex than mine and they (Rugged Circuits and WilliamK) are selling fully loaded and tested boards for $100, hell the 2560 processor I'm using is $27 by itself (small qtys but that's what I'd be buying) and to be honest the thought of making more that 1 or 2 sends chills down my spine
So it gets back to having a Chinese company build them. I gather Seedstudios will quote, I might drop them a line because without a reasonable chance of cheap manufacture there's no point.