Criminal Law Questions? Ask a Criminal Lawyer.
DearCustomer- Whoever wrote the check is guilty of a crime for writing a bad check and possibly other charges such as theft by deception. If you were selling for the artist then you are responsible to him or her for the money but you have no criminal liability since you had no knowledge of the check being bad.
Obviously you can also sue whoever wrote the check for either the money or a return of the item. Hopefully you can locate this person and you definitely need to call the police.