Some people buy cameras in Hong Kong several hundred to 1,000 yuan cheaper than those in China. What's going on here?

Hong Kong is a free port and goods are duty-free. For example, if the camera you mentioned is not made in China, you will have to pay a certain percentage of tariffs if you enter the domestic market and go through normal channels, so it is normal to spend several hundred yuan or one thousand yuan.

The proportion of tariffs is different, and the proportion of different goods in different countries is different.