I guarantee that Badspot had some kind of contract with gamedujour where they bought 500 keys off him at a discounted rate for resale. Both parties benefit, Badspot gets all that cash in one lump some and gamedujour gets profit whenever they sell a key. Badspot wouldn't advertise this site because he's already gotten the cash from those keys, he doesn't get any more when you buy a key from Plimus/gamedujour.
Also, blatant ID discrimination has always resulted in bans.