Jed, Mick, Susan, DebC -

Great points. I also practice the discount for multiple purchases, with $15 being the cost for one here in the U.S.

Tom Bliss's explanation of expenses is also pretty accurate.

I play at festivals and concert venues that take up to 20% for allowing us (the performers) the privilege of selling our CDs.
Their rationale is that they are providing a retail platform for us to sell, therefore they are entitled to charge us for said privilege.

At some venues, sales are wonderful, so I don't mind paying the 20%;
at others sales are horrible, so I resent paying the 20%, but I still have to pay it if I want to sell at all.

I've begun dropping the jewel-case format, and moved to paper/cardboard wallet format with my CDs. They are lighter, narrower (therefore you can fit more to a case), cheaper to mail, and they don't crack or break.
Something that bothers me is a person refusing to buy a CD because there's a crack in the jewel-case - even though the CD itself is unscathed. In those cases, I'll knock a couple of bucks off the price.

Ultimately, I'd love to have some format at a show whereby I can sell downloads of individual songs to purchasers ( folks at my shows usually buy a CD because of one particular song they've heard) in the same time that it takes to sell a CD.

Seamus