Cheap stuff is generally cheap for a reason. It is in the name. Paying $250 for a used bikes direct bike unless it wasn't actually used is overpaying. I would rather spend $800 on a good quality bike (not just something overpriced) I am going to ride a lot and enjoy than overpriced used garbage.

Basically you are wondering why Pepe's Pizza in New Haven Connecticut costs so much (it doesn't but it is the best pizza) when you can go down to Little Ceasars and get a pizza like object for $5 bucks?

People these days are getting cheaper and cheaper and cheaper to the point that unless it is putrid garbage they won't pay for it.