Anytime I have needed quotes for anything, I had good luck going to :
http://www.basements101.com/contractor.html
There are 3 or 4 contractor locating services listed on 1 page. You can type in your information, indicating the type of quotes you are looking for and they will have the "qualified" contractors in your area contact you. All free of course.
This seems to work great. I have tried to call contractors from the phone book and 90% of them seem like they just don't want to call you back.
I also schedule 2 or 3 contractors to look at the project at the same time, this way if 1 doesn't show up, I don't waste my time waiting for him and if they all show up "on time" they may be a little more competitive! Hope this helps!