Actually, there are two ways of earning through wearing a signature campaign, paying Bitcoin which can be found here, and a fancy token which is found it here.
You can visit the thread of any of the signature campaigns found on the list given above and calculate it on your own or check the spreadsheet where all costs of the company in the signature campaign were recorded it there.

No, not all of them, as long as you aren't trolling here you'll be fine, and look, you received rewards from them(merit).