Looking at all the 'negative' comments about Udemy's marketing/discounts, I get a feeling there is a maybe small market for a niche Udemy (high cost courses/ no discounts/ gimmicks)
One that I can think of is "Selenium 2 WebDriver Basics With Java". The the topic is niche, and the course seems comprehensive. And for the price tag, it somehow never gets to the discount bin(I know this since its been on my wishlist for so long).
If the price is cheap, I would bought this as a casual learner, but if I am really into testing with Selenium, I would not mind at all paying the full price.
With the price, that course garners something like 800+ students. So if you are into supporting your student when they are going through the course, charging high is the way to go IMO.