Specialized branded components can cost a heck of a lot. Also, note that you just said "i can't find any electronics sources that sell them." So, rare, not standard production, possibly manufactured just for EMG.
I just Googled around and found
this diyAudio thread. They are/were having a hard time sourcing these pots as well, and were trying (unsuccessfully) to get enough orders together as a group to get a
wholesale shipment of 250 pots for $25 each. Good luck!