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.
Camel was one of the first for Amazon shopobot just looks to be a copy of the same idea. Look at how much price history camel has. It goes back over 3 years for some stuff.