Most Architects that do residential work can help you with this type pf work. As per cost, you should consult 1or 2 Archittects and ask them directly. However remember you choose a doctor, lawyer, etc by skill and not by cost...
PyramidDG.com

Where we are located (Vancouver Canada) phased renovation is work is very common. We have had numerous clients who needed to phase their projects, whether it be for practicality or monitory reasons. You have the right strategy, in my opinion: think and plan for the entirety of what you want to do, then devise a logical plan to break the work into components. Phased projects do have a tendency to be more expensive overall, and cost savings can usually be had by doing everything at once. However, the schedule needs to be the right fit for your particular requirements. A good residential Architect or designer should be able to help you through this process. I would contact several in your area regarding fees.

We offer a number of free resources on our website that may help you in these initial planning stages. Please feel free to take advantage of them:
http://www.gronlunddare.com/?page_id=692

your welcome, dansalva! I was glad to see you took advantage of the free download. Good luck with your project.

You want to make sure you find someone who has done *remodeling* work. Some architects only do commercial. Even a residential architect or designer, if they have not done remodeling work, I would suggest you don't waste your time.

Prices can vary. I personally meet with each client to understand the scope of work before quoting. Also, check with your local governing body and see if they require a licensed architect or if designer drawings are accepted. If there is structural work, they may require an engineer's stamp - usually a reference from the person with whom you work to d othe design.