The LA Times says that the pricing structure will be based on popularity, "true to supply-and-demand economics." (Except that you know, there is limitless supply here, but whatever.) New artists will be the ones most likely to have their tracks sold for 69 cents a pop. Even classics that are perpetually loved by the masses—the LA Times mentions "Born in the USA" could go for $1.29.
99 cents is such a psychologically satisfying price—it's not even a dollar, as this really annoying Coke radio ad I kept hearing over the weekend pounded into my brain. It doesn't take a genius to see that $1.29 tracks are going to sell way less than they would if they were 99 cents, because the purchase officially moves from impulse level to the lower rung of "well, lemme think about it" territory. [LA Times - Thanks Ray!]