Confused with Hikvision model numbers? And features included in specific cameras? Please have a look at this easy-to-read spreadsheet. It'll also give you the prices of cameras from three reputable sellers, it is safe to order from them. In this thread, you can also ask about differences of the models.
Important thing to note:
If you purchase a Hikvision camera / NVR from Aliexpress, you should not upgrade the firmware. If you upgrade it, the user interface will be in Chinese only. Despite there are some solutions to this issue, it's better not to upgrade the firmware if you are unsure.