This one's a bit of a workaround, but O'Reilly offers eBook versions of many of its titles considerably cheaper than their print counterparts. All you really need is the ISBN number of the title you want. A thread over at OzBargain details what you need to do; given the steps I've got a sneaking suspicion that O'Reilly knows all about this and does nothing to discourage it. All you have to do is:
• Register an O'Reilly account at https://members.oreilly.com/account/login • Go to https://members.oreilly.com/account/register/index, add the ISBN number. • Go to https://members.oreilly.com/account/emedia, click "Print Books" tab. From there you can purchase the eBook versions directly.