The best place would be Harvey Norman because they do accept booking... just walk in to any branch and put your name on the waiting list. They will call you the moment they receive new stock. Otherwise, Apple store will get their stock every Wed-Thurs... need to try your luck.

I would advise against buying from Gemfive unless you check with the seller on the stock availability. I had a bad experience earlier this week as the seller did not have stock, and the amount was charged to my credit card. I had to email Gemfive for a refund.