Ani-Com (ACGHK) is an anime/comic exhibition/conference. In 2013, it will take place from 26th to 30th July. My question is when is the best time (day, and time of day) to go? When will there be less people? When will the prices go down? Will products be sold out if I go on the last day?
Definitely on Friday, come as soon as possible. Once the weekend starts and people come from work or school (Friday from 16:00 on), it gets packed very quickly. People start lining up overnight to get the best stuff anyhow. You can assume that once the prices go down, the good things will be gone, too.
The visitor numbers have been increasing massively over the years, so be prepared for a VERY packed convention center.
If I remember correctly I have been there 2 years ago on Sunday and it felt more like a plucked chicken then anything else. Also, most of the exhibits there (apart from hardware) was geared towards Chinese/HKG anime, not so much (as far as I could tell) Japanese/International stuff. It can be however that this changed since then since the fair expanded quite a lot since then.