They're a part of the affiliate program, and they are price tracking, so I would say they have implicit permission, or else they would have been long kicked off of the affiliate program.
I recall reading that the reason CamelCamelCamel is permitted is because they ONLY price track Amazon (vs tracking multiple retailers), but I can't recall where that came from.
I recall reading that the reason CamelCamelCamel is permitted is because they ONLY price track Amazon (vs tracking multiple retailers), but I can't recall where that came from.