Your could try the Australian medicines handbook
by the Royal Australian College of General Practitioners, Australasian Society of Clinical and Experimental Pharmacologists and Toxicologists, Pharmaceutical Society of Australia. At work I use a combination of MIMS
(available electronically) and the most recent copy of the injectables handbook, and at home have a laypersons guide, The Australian drug guide : every person's guide to prescription and over-the-counter medicines, street drugs, vaccines, vitamins and minerals
by Jonathan Upfal. If you're already familiar with most drugs but want to know about trade names this is a far cheaper option - it alphabetically lists drugs by generic name (followed by a list of trade names), includes classification and a brief description of the mode of action, and outlines side effects and adverse reactions by severity. There's also a section for each drug on interactions with other drugs, food and alcohol.
is a great, Australian online book store, but you might consider looking at either a university bookshop or, if you plan on buying a few books over the next year or so, you could try Readers' Feast (in the city), which has a free membership program and gives you 10% of your spend back twice a year as a voucher. That way you get a reward but also get to claim the full amount of the textbook as a tax deduction