[Panda]

Can I have an art shop in my selling and buying shop in the marketplace?

[Toriki]

You mean like a part of a post where you offer your arts in your selling thread? Yes, as long as the selling still goes, the art can be as well. Though make sure the art-selling isn't primary objective of the thread. Other wise it'll go to the Art Royale.

[Immamoonkin]

This should really go in the suggestion thread, and I had to change the title of your post because it sounded like there was a real issue with the store (like a bug).