Thank you, Eric.
Some parts I already had on hand, like sockets. I buy them by the 100 at a time, so, prices are lower, and I don't use the machine pin sockets except where absolutely required, like for the stacking you're describing. A good quality dual wipe socket costs 20 cents in quantity, versus a few dollars cost for machine pin sockets. The most expensive parts are the Molex connectors (sadly, the 2pin and 6pin headers are out of stock everywhere until January 2022)and the long pin headers (Samtech brand, 13mm long -- those cost $6 each, and, sadly, I ordered too few of them). I also buy capacitors and resistors in multiples of at least 10, which often times drops the price to less than buying, say, 6 of them versus the quantity breaks at 10 pieces. Resistors and ceramic caps I buy at least 100 at a time to get them down to pennies. I also did not buy anything to populate the video slots, as I don't exactly know what it is used for. It looks the the OG has a secondary PCB that those mount to, at a right angle. I also did not buy the GALS (or PALs, whichever it calls for), as those aren't listed in the Github BOM, so, that too could drive the cost up.
Thank you for telling me about the 3D printed guides for placement. I did not know of their existence.
I did find higher resolution pictures on http://amiga.resource.cx
, so I now know how the pins are supposed to be done. I am assuming the fixes that you mentioned are the elimination of the various bodge wire jumpers the original had on the underside to fix some mis-routing?