Suggestions for buttons? (Patreon)

Happy Friday fans!! Just had a thought of trying out making buttons featuring the faces of my characters. Perhaps 5? I would like some feedback from my patrons on the type of works I should use (face only) and for the price in SGD that people would be willing to buy each! You can view my past works at either tumblr, instagram or patreon :D Thanks! (image isn't my works. For illustrative purposes)