I'm honestly not sure. Team Xecuter has been around for decades so there must be some profit in mod chips, but I don't really know how they do in terms of numbers. I know some time ago adafruit or one of those *unio companies did a run of NES controller sockets.... they sold them for 2 bucks a piece, which is probably a little overpriced for what they are, but is still more than reasonable.
I'm really interested on the logistics involved in doing specialty parts like that.... it seems like the things missing a lot in this hobby are the misc widgets. Like volcano buttons were scarce back in the day and what-not.
Just thinking aloud though.