Great concept, but are they getting the best price on the best one? Buying the best <X> is good, buying it at the best possible price is better.
We pick the price we show from Reevoo's price comparison, choosing the cheapest price from the 400 shops we list prices from - so we're pretty confident we're showing the best product at the best possible price. I'd love to know if we're missing somewhere with dirt-cheap prices, though.
One caveat is that we don't use Amazon Used&New prices for JBTO, just cause things tend to be sold in very low quantity there and so go out of stock really quickly.