Despite the logic of Dee's answer, if there are reasons you want to stay in the area, Linda's answer is partially correct. You might want to consider contacting a residential designer/architect to work with you on the redesign. This will provide you with a quality set of plans that will be needed by the city/county for permitting and it will give you the opportunity to have several builders big the project without having to start all over again with new plans. A contractor is not going to give you the plans their in-house designer creates if you want to get more than one bid.
Contact AIBD.org to find a qualified designer in your area.