Someone, who will remain unnamed here, got me interested in building a Megatron
I got quotes back from the fab houses. If we can get 10 sets we can get the cost per board down to just under $40 USD (plus shipping from me to the participant). The PCB is 228mm x 228mm and will be 2mm thick with 4oz copper.
I did some research and the only obsolete/hard-to-get part is the 4 2SA1968 which Kevin confirmed can be replace with KSA1156 mounted backwards. The board also uses 2 2SC1815 or MPSW06. I have a stack of the 2SC1815 so I am happy to supply them to the GB participants that need them (no cost).
Please respond here if you are interested.
Thanks!