Go to Tuen Mun Hang On Provisional wholesale,they have a good quality but cheap price olive oil called Sensa olive oil,about $40 per litre,glass bottle,good for both salad and cooking.
Hope this can help.
Address is near HK Ham factory in a Industrial buiding G/F
Tuen Mun Ind Centre if they have nor move out?
The Map http://www.centamap.com/gc/home.aspx
Thomas
