Its hard to say how many classes are considered to be too much.
is because it will all depend on what type of products you will be
selling on your site, and therefore, how many classes you may need to accommodate all your products into categories.
For example, if I were
selling Computers, then some of my classes may include "Desktop",
"Notebooks", "Storage", "Accessories", "Memory", etc....
really depends on what you are selling and how exactly you would like
to categorize your products.
Setting up classes would be your personal
preference and you will need to first figure out what you will be
selling and based on that, try to come up with a list of classes that
you can use to categorize your products properly.
If you have any additional questions, please let us know.