So I’ve seen xenforo forum software has an option for people to set colored usernames for others and like a marketplace plugin for users to buy those cosmetic perks, does discourse have this? if not could it be implemented?
For example I want the color red on a discourse forum. I buy it through a paypal integration or just direct pay the owner for it, and the system or owner will set the color to red for me. so my username will look red everywhere on the forum 
If a user has a primary group (which can be configured from the admin UI per user) you can style the user however you want via CSS, including making the username puce if you will. 
There is no end user control for this.
so its done through code? can’t be done admin UI entirely with the price?
You can edit the CSS through the admin panel, so it already can be done through the admin UI.
I’m talking about the paypal integration thingy. cuz xenforo has that for
user upgrade section or something.
With the following plugin, yes