Using the code "fdkY9rd" on checkout, you can currently get 90% off the price of *many* eBooks. Note that this does not apply to ALL eBooks (in particular it is unlikely to work on most latest releases) plus you need to buy one book at a time as the discount only applies to the first book in your cart. Note also that my credit card was suspended as a security measure (lots of micro payments are seen to be suspicious) after about a dozen or so books (had to call them to re-enable it) so if that's a concern then might be better off using paypal or buying a gift card and loading that onto your account first (with the risk that by the time you've done that the code may no longer be valid). Anyhow, I reckon this is a great deal. Have bought a Kobo Mini (currently $49 at JB HiFi and DJs) for the kids to use, and bought quite a few kids books to load onto it.
Although I believe this to be a brilliant bargain, be aware that most books are "DRM" ie locked to your device. Both my wife and I have Kindles, so because of the protection the only way we could read these books on our kindles would be to remove the copy protection - possible, but a hassle as well as a grey area as far as legality is concerned.