I would get several estimates from different contractors and present an estimate with the counter. You will have a much stronger leg to stand on. If you can use websites like Angie's List or the Better Business Bureau to find reputable contractors. Make sure you get an estimate for the whole job, not just the re-piping-- it will be necessary to cut wholes in the walls in several places, repair each whole and re-paint to match the previous paint color.
Repiping in our location can be done in the $3,000-$8,000 price range. Our recommendation is to have a local plumber provide you with a written estimate to have this work done. Written documentation can be a powerful tool.
I just heard from one of my past clients -- she had had her whole house replumbed in 1999 with the PB class-action money. Problem is, they used PVC. One week before Christmas the PVC sprung 3 leaks in the hot water line- EEK! Now they are replumbing the whole house AGAIN! Her plumber, as well as the one we just used on one of my rental properties recommend using PEX