John Perry Barlow says:

Also, from an economic standpoint, many musicians have discovered, as the Grateful Dead did, that the best way to make money from music is to give it away. While scarcity may increase the value of physical goods, such as CD's, the opposite applies to information. In a dematerialized information economy, there is an equally strong relationship between familiarity and value. If your work is good, allowing what you've done to self-replicate freely increases demand for what you haven't done yet, whether by live performances or by charging online for the download of new work. "

Or maybe by paying after you know you like it.