?? means you can pay whatever amount seems appropriate. I suggest the following interpretation of ??
Main set: Two KRW1,000 notes, a handful of loose gravel, and a small bag of Fritos
Tsangan Set: Three pounds of frozen broccoli.
Tenkey set: The July 18, 1975 TV Guide.
Okay, I'm entirely too silly.
Serious: I'm looking over the old discussion, and it seems like the Round 1 order got down to 49 USD per set (for a full 104 set). How many sets did we order for that one? AFAIK, 200+ is a record.
Also, the centre stem stepped thing really closed the sale for me. That always annoyed me on the Filco, Ducky, Cherry 8100/8200 designs-- you're stuck with a full-size key there which always fouls.