Maybe it's including time invested into development? The F1C100s is $5 for one piece on AliExpress, all the parts seem to be solderable by hand/manual reflow i

Maybe it's including time invested into development? The F1C100s is $5 for one piece on AliExpress, all the parts seem to be solderable by hand/manual reflow in an hour (the passives can be populated by JLC for like $30 for a batch of 5 boards, saving your time), the board would be $2/piece for a batch of 5 at JLCPCB (seems to be 2-layer), the enclosure can also be 3D-printed on a professional printer at JLC for tens of $, the only thing I don't have experience with is the conductive-rubber keyboard.