I have two 4MB memory expansion cards for sale or trade that I built from Golga's design (see original
Galspanic thread (https://nfggames.com/forum2/index.php?msg=49433)).
One card is on 1.2mm green PCB, the other card is on 1.6mm black PCB (kind of hard to get into the slot).
Price is $50 + shipping per card.