As stated above, I do think its a market related thing. In our case, design time gets built into every project as part of the bottom line as a percentage of the job. This works well for us as jobs that are 50K and below only take about an hour or two to quote. If we don't get the job, I'm not out a whole lot of money. As the job price increases we get exponentially more profit. Any job over 100K is considered custom and then we setup a design fee up front depending on the complexity of the job.

In our market, we find our competitors will throw something together, close the sale, then change order the customer to death. We prefer to have a system fully specified going into it, even if it means us losing a couple of billable hours of labor, because in the end it's going to be right and we'll have a staisified customer.