Hi Isabel, thank you for your comment 
I have shared some cats drawings with eyes and expressions before.
Like:
Cute? kitten in a babywear
Cat cat cat…practice really works
Calico cat & butterfly
Black cat with a ballpoint pen
Yes, I am aware of that particular market, but I think the most popular art items in the market is hyper-realistic portrait type of paintings/drawings. I may go into that path in the future but right now my purpose is to establish the style for my new animated film, where many, many cats will be starring