The true cost per sq foot to build in Santa Rosa

We’ve been doing some more analysis of actual costs in Santa Rosa and are seeing that the average cost per square foot is around $350 with some estimates going as high as $800 per sq ft. A lot of sites out there seem to be suggesting the cost is around $150, based off really questionable data, and I wonder whether this is creating friction with clients who have unrealistic expectations for how much a build should cost?