This is a great question, and the answer is...it depends.
Not all builders have the resources to offer services within the Design Development phase of a project, however there are a number of builders that do provide this service.
MudgeCorp offers a Design Development service and we have great relationships with consultants like architects, designers and engineers. By collaborating with the experts in each field we can come up with the perfect solution for your project.
Take a look at our Essential Checklist for a little more info on the 'design phase' http://www.mudgecorp.com.au/your-essential-checklist.