It varies by each individual office. Laser whitening is always more expensive for the dentist (time) and thus the consumer. You could probably find it for $350 though. Google Dr. Kathy Frazar and Tom Hedge. They're married and have a fantastic practice in Houston.
The price for Zoom in-office whitening varies between individual offices as well as by location. You may even find advertised prices ranging from $99 to $600 but take precaution when selecting where to go and do not base your selection solely on price.
Finding an office that you can trust and feel comfortable with for any type of procedure is very important. You can ask for referrals from family, friends and co-workers, or even visit the prospective offices and ask questions you may have prior to deciding where to complete treatment so as to achieve the most pain-free and satisfactory experience that is worth the price you pay.