Seven of Greg Egan's books that are published outside the US by Hachette (and sell for £4.99 in UK and over $10 in Aust./Canada/NZ), are now being self-published for the US market on Amazon and iTunes at $2.99 each. See the
author's announcement dated 30 July.
I'm not sure whether $2.99 is a limited-time special or will be the normal US price.
The seven books are: Quarantine, Distress, Diaspora, Teranesia, Schild's Ladder, Luminous, Oceanic.