the only reason not to sell or promote the c.d. would be if it had a song by the "other" performer on it! Often performers are paid less than a living wage....and product sales make up the difference... like a waiter or waitress getting less than minimum wage....it is EXPECTED that they will get tips/gratuities commensurate with their service (or in this case music) If you are lucky the venue will NOT require a commission on sales as I have seen some laces require.