NetSuite is way too complex and varied a product for a $20 Udemy course to even begin to cover. However, there are a number of publications you could also use in preparation for the exam. In consideration to the knowledge you would gain after the 2 days course, the NetSuite courses aren’t that bad value wise. Alternatively, you can gain the required knowledge after using NetSuite over a period of time, this acquired knowledge is of much greater value than just finding the answers online. You need to think about why you want the certification.