Don't feel you need to buy everything (I kind of did that)
Checkpoints are great but some people feel they distort the difficulty of exams. If you rather save the VCAA questions for later in the year, NEAP apparently sells questions and the ATAR notes topic tests are meant to be great as well.
If you're looking for a summary book, the ATAR notes book is great, other alternatives include A+ biol notes which has some great diagrams (and great practise questions) and the TSFX lecture notes if you can get your hands on those which follow the study points both concisely and accurately.
Again, don't feel you need to buy anything at all, the school textbook is absolutely sufficient if you make your own notes throughout the year which are always better than simply reading someone elses.
Good luck!