I'm sure any good study would confirm what my friend (a record store manager) says: while new CD sales have dropped, the sales of used CDs have remained constant. Why would this be the case? Perhaps they are reasonably priced?
The record companies' response to file sharing was to raise CD prices yet again (to make up for losses), but this just drove more people from the stores. And then the RIAA screams even louder about "piracy". Wrong again. It's what happens when corporations become reliant on legislation-for-sale rather than good business practices to get ahead.