The majority of links are to Amazon's product listing. Sometimes with alternate links (I've seen Jet.com and Homedepot.com type links). All reliable web stores.

You're right that its percentage based, so there may be a slight bias toward higher priced items, but I haven't seen it. I bought a recommended non-stick pan off thesweethome yesterday, and they explicitly talk about price range being good to go a bit cheaper and just buy a new one more often, rather than a more expensive one (to minimize the effects of wear that hit even expensive ones). So they recommend a cheaper pan than they could have.