Depends a lot. If you want it fully assembled, you have to go to larger fab houses like PCBway, and spend a few hundred bucks on a 5pc batch. If you can hand-solder some parts (in this case, the Bluetooth module and the USB connector) and design the rest around jlcpcbs libraries, you can get away with 20-30USD per unit (MOQ of 5) plus shipping/customs. Then add another 10USD for the bluetooth module and USB connector.

A simpler wired design like my E80-1800 (https://github.com/ebastler/E80-1800) can be completely assembled by jlc for ~30ish USD per unit.

Oddly enough, small-batch prototyping at jlc can be cheaper than medium sized (50-150 pc) runs at other fabs.

Hope this doesn't sound like an ad, I've compared a lot of prices and nobody came close to jlcpcb, but With their limitations (limited stock, limited finish/color choices, frequently chnaging stocks and component prices) and sometimes far-from-ideal QC (some scratches can happen, in rare cases even missing components that were present in the BOM) they are not really my first choice for production runs. For prototypes or small unofficial-ish batches with a few friends though - god tier.