I've noticed that when you've bought a bold, italics or coloured username item from the shop, you can't buy it again this has already been reported but this goes for all the other items aswell, and it is not happening only to one person..

Maybe you've imposed a limit to only allow one purchase per item per user?

Well, it just gets kind of annoying for people who constantly want to change the colour of their username, personally it doesn't really matter to me just pointing out a bug or a misconfiguartion in the shop..