There are many contractors out there. Some are reputable and some are not. Often times I give a person an estimate for a project and they find another contractor who will do the work for less. Many months later we’ll get a call for another estimate because the contractor left in the middle of the project or did a poor job. In these cases, the price increases because you have to tear out the work that was done and start from scratch. The owner has already given a big chunk of their money to the other contractor and is left with a shoddy job.
Something to consider when you receive an estimate would be, is the contractor well regarded? Will he finish the job? Does he do good work? All these things can be found with a little due diligence. Get referrals, check the Better Business Bureau, check the California State License Board and check social media sites. If you put in the work, you will find the right contractor for you but just remember, your home is the biggest investment most people make in their lives. If one contractor is 5% or 10% higher but you feel a lot more comfortable working with him, there may be a good reason for that. Paying a slightly higher price in the beginning may alleviate change orders, cutting corners and hiring a less than stellar contractor.