Not sure there is such a thing as a "advanced course" but you may want to consider a few business classes/courses on business and how to create a business and cost models so that you can make a profit, if that is your goal, from selling products.
Being an expert at knowing how to list and sell on eBay is one thing but knowing how to handle the business aspects is another. Things like sourcing, inventory, risks, taxes, etc. are things you are not going to learn from eBay courses there are too many variables.
