Just yesterday I bought a HKG-NRT-HKG Y class ticket via www.unitedairlines.com.hk for only HK$2600. Out on Aug 26 back 3 days later. Playing around with it I saw a lot of other good deals to the US (HK$5500 to SF on Aug. 27 for example). They don't seem to advertise them but if you look around, in my experience, you're able to find some good deals that travel agents have not typically offered me. Good luck.