Don't they need to sell with a "warranty" to get the higher prices?

In the US market there are some power sellers who say 2 year warranty and get big prices. Meanwhile while I was selling 1 as a non-prof seller I got tons of questions of "can I return it" and "what is the warranty" and two times my item was bid up to the stratosphere by non paying biders. Finally I listed it buy it now only and eventually a no fuss buyer bought it for half the price of the prof-sellers.

My point is, ebay prices don't always tell the whole story.