I assume you're asking what price you should fix for your course so others could purchase it from Udemy marketplace. Well, you can fix the cost whatever you want!...You can do a rough approximation about the worth of your course by looking at other similar courses - their popularity, course duration, instructors' profiles, language of instruction...they are many factors involved. Look at similar courses and decide. You can also start with lesser than the average cost of courses in your niche if that, you think, can attract students to your course. As a seller, you decide how much worthy your course is.