Theres no easy answer to your question since there are many factors to consider when setting your course price. Here are a few suggestions:
If you have your course on other e-learning sites be sure to keep your price consistent. Keep your price as low as possible, but look around Udemy to see if there are similar courses and price competitively. You can sort courses by category in our site search to more easily find courses similar to yours.
Once you set a course price, you can offer different coupon codes to give your course away at a discount. While you can change the price of your course at any time, you can switch from Free to Paid only once. If you switch from free to paid and back to free (or vice versa) after the course is published, your promotional announcements for the course will be permanently disabled.