Our experience with Petfinder has been awful. They won't respond in a timely manner. The decided the rescue prices were too high though they were in line with the area so stopped replying at all and would not give approval. Yet they allow breed specific rescues to charge $400 for adoptions.
I think Petfinder is using their position to bully new rescues. If you require a certain pricing then you need to make that information available. Rescues are folding all the time because they try to keep prices low but find out that the costs of vetting and maintaining animals can cause issues with sustainability.
I have found Petfinder representatives to be unprofessional, and hoping that some of the other pet search websites mange to take over the market. This has caused a great hardship for our start up rescue and all because we ended up with one representative that decided to dictate to us.