You can create up to 300 Store categories. Your Store category total includes the sum of all level 1, level 2, and level 3 categories. For example, you could have 300 level 1 categories or 30 level 1 categories with 10 subcategories each. You will want to note that eBay automatically creates a default level 1 category named 'Other Items' that cannot be edited and does count towards the 300 category limit.