I've just finished my HSC. And most of your subject selections are very similar to mine. I would highly recommend the Success One HSC Business Studies past paper book. It definitely helped me come first in Business Studies in my school, as it provides abundant past HSC papers and full solutions to give you sufficient practise before the actual HSC.
Also Cambridge Checkpoint Economics is the only past paper book available for economics, that has full worked solutions. Highly recommend this, because the boardofstudies does not provide fully worked solutions to past papers. And remember "practice makes perfect" !!!
Success One Mathematics (2 unit) and also Success One Mathematics Extension 1 (3 Unit) highly effective.
These books are highly beneficial!!!! Feel free to contact me, as i can sell them at MASSIVE DISCOUNTS to you.
All in good condition.