I think that if you're going to sell cosplay, you should do something more detailed. If you want to sell clothing items, you definately need some variety. So for example, a cosplay would be a costume from an anime/video game - rather than just a shirt.
If you're looking at selling cosplay, go for popular anime looks. Maybe like hats or shirt + skirt type outfits. If you want to sell shirts, I like what you designed. You may want to look into different colors and perhaps even more detailed designs. Be sure to have a variety of sizes though!