The course fee depends on the course of your interest. You can find the fee and a description of what is included in the fee on the course page.
For several courses there is a difference between the regular course fee and the (lower) student fee. Are you currently enrolled at an institute of higher education? This will most likely mean that you can pay the student fee.
Some courses offer special discounts such as an Early Bird or scholarships. If this is the case it is clearly described on the course page.