Been digging into the skin trading markets for quite a while now, thought it would be a good idea to "measure" how big it is by checking how many users do all the known sites get.
Found a total of 42 sites which all amounted to 53 million monthly visitors. There are instances of sites that have a majority of visitors from one region, such as Lis-Skins, Market.CSGO has a lot of Russian traffic, SkinBaron with German.
Quick note: I didn't include any Chinese sites since I was unsure about the data there. For example, Buff showed up as 2.5M which I think is too low.
Numbers are from 2025 July and sourced from SimilarWeb.