If you find that you end up wanting to make some kind of web scraper, you can copy some of the code I wrote awhile ago if you want. When I saw this post I decided to upload a python web app that uses webscraping to get a specific user’s total sales that I had laying around. In order to do this, it has to go through all the groups that the player has publishing permissions in and checks the group uploads for items that they uploaded. Just so you know though, this is not scalable because of the massive amount of requests it would require for a larger number of players.
[EDIT]: I removed the link because it doesn’t work anymore since clothing sales are no longer publicly available.