I've coached a few adult goalie clinics and the numbers are weak compared to forwards clinics. Some guys (and gals) are willing to get a hand in brushing up on their skills but it's not many. While I was with the organization, I was asked to take care of 4-5 sessions, then it died off, not much interest.
Aside from the organization I worked with, I've only seen one other advertisement for adult goalie classes/clinics in the Québec area.
I've been trying to solicit some students of my own as an independent coach for a few years and the interest in my city is very low. This doesn't mean that there is no possibilities elsewhere. There's a market, albeit small but still one.