That is also my understanding, and a good plan. I've been surprised how negotiable the price is down at Teds... Bear in mind that you are likely to have to cough up GST upon your return to Australia if your purchases are above a certain amount (they always are for me).
There's a good reference for current HK lens prices here:
http://www.ygdragon.net/ Just click on "
Lens Price Reference List 鏡頭價目表" on that page. This is not a shop, it's a list of recent sales per lens. The prices shown are generally very competitive, but it's up to you to negotiate. :)
woodbe.