How do you know if you are paying too much for a CPA?

[Juliette Lerner]

Is there an average price to pay for multi-state tax returns (3 commercial and 3 residential rental properties) in California? I believe I am being overcharged but it seems like a huge risk to search for and switch CPAs if that is the case. How would I reliably know that another CPA will do a good job for less money? Any advice on potentially switching CPAs or what to do if you think you are being overcharged is very much appreciated!