These services already exist, although I don’t believe they use the implementation you describe. Instead they’re basically coupon collectors. They just find the lowest available price and route you to it, or something like that. (I don’t use any of them, but they advertize to me relentlessly. I should probably try them out, actually.)
That's interesting. Are they actually using personalization to get better prices?
I'm thinking of scenarios where if two different browsers visit the same page, they'll get shown different prices depending on their cookies etc. In that case, a third-party site can't really "route you" to a lowest available price, they have to help you make the purchase from the right browser environment.
