Tony: If this is something you have not done (and it sounds like you haven't), I would definitely have a licensed electrician do it. However, I'd look through your local community paper under "services offered", where you can often find a licensed electrician who either moonlites or is retired. When you call for a bid, ask if you can help him do the work. This benefits you by helping to keep the cost down, but also helping you to understand how it works. I have often found that the retired electrician will talk your ear off (smile).
The price of the job depends on the condition of your box and wire, how difficult it will be to access your wall cavities/basement ceiling joists and how much wire you run. 90% of the work will be running wire. If you don't mind doing the labor, you might try to have the electrician assess what you need, show you where to run the wire, leave and let you do the labor and then once the wire is in place, come back and do the hook up. This would be optimal....but unfortunately, it rarely turns out that way :-)