I went through a similar situation in April, when I had to go to Hong Kong for a family emergency. Going there was no problem, but coming back was a nightmare due to the way my parents had booked my flight. I could only go for a week due to my job, but somehow my parents had booked me for three weeks instead of a week on the return flight. In the end, I forked over 600-700 US dollars to a travel agency in HK for a one way ticket back to NYC two days before the flight. Overall, I would say 800-900 is not that bad on last minute. You can take a chance with the airlines, but the most likely outcome is they would rob you blind since they give you ridiculous price quotes that were literally 3 to 4 times the amount I got from the agency. I know since I called every airline going in/out of HK and every time I called I got sticker shock. I guess this is probably how the airlines re-coup on all the cheap fares.