This really depends on the size and scope of your project. The materials chosen, the size of the room, and age of the infrastructure can all impact the project cost. Remember when you are comparing bids that you are comparing the exact same scope from each contractor.
Building codes have been established by most cities, towns and countries. They vary considerably from one jurisdiction to another. A building permit generally is required whenever structural work is involved or when the basic living area of the home is to be changed. A professional who works in your city or town every day will know to local requirements. If your project does require a permit—and your remodeling professional asks you to pull the permit—this should be a red flag. The professional you hire should be in charge of obtaining the necessary permits.
How long have you been in business? Who will be assigned as project supervisor for the job? Who will be working on the project? Are they employees or subcontractors? Does your company carry workers compensation and liability insurance? What is your approach to a project such as this? How many projects like mine have you completed in the past year? May I have a list of reference from those projects?