I am certain the sale of CDs is not just an issue of cost. I think most CD buyers already have too many CDs.

I play concerts and sell CDs at full price typically ($15), but offer a discount to encourage purchase of multiples ... and that seems to work. I play festivals and often offer the same deal.

When I play pubs - I usually sell CDs at full price. The audience at pubs is less likely to buy many CDs. BUT at pubs people fill the tip jar. It strikes me that every night at pubs, someone or two or three people will throw a $20 in the tip jar. If they'd have taken a CD, I'd have had to give them change!! To me that says, they really appreciate the music, they want to express their appreciation (and it is almost alway anonomous) BUT they don't care to bring home a CD!