It's all a case of suggestive marketing IMO. The internet will automatically suggest better pricing for everything and anything you come across.
This is the primary reason it is always advised that you research & carefully analyze every bit and aspect before delving head first into any kind of online business.
Coupons, Discounts, Hookups etc. - the internet is laden with them. But given the magnitude of people logging onto the internet everyday and finding sites which claim that they can "easily start a business of their own by reselling domains" - it is pretty obvious that overprices sites like these are making sales.