Agreed, but I'm not sure if they'll be able to keep at it I looked at building something similar a while back but found most of the big retailers (Amazon, eBay

Agreed, but I'm not sure if they'll be able to keep at it I looked at building something similar a while back but found most of the big retailers (Amazon, eBay) prohibited you from storing historical price data. Unless that's changed I'm not sure their approach is going to be feasible in the long term.