I wish everyone here would read what MRP and Ascended has written in this thread. Even if they don't know the business side of comics, they do know economics, and has applied that knowledge well.

MRP had a great post on price sensitivity. Another thing to remember is that the nice smooth curves (or lines) between price, demand, and supply beloved in Economics 101 are mostly a fantasy. One comic book title is not exchangable for another, and different readers have different curves. A reader might happily buy five floppies at the $3.99 or $2.99 pricepoints, but go to zero or one at the $4.99 price point. At the same time, reaching a big proportion of the prospective buyers at a $1.99 or $2.99 pricepoints is probably out of reach for DC, given the way the direct market is set up.

So Dan DiDio is almost certainly correct that the comics market is price insensitive, but it is only known to be sothe constraints of the direct market and the price points that DC has explored.