Water hammer, dripping faucet in bathroom
There are alternatives to try first before spending more money. See this link...

http://www.dummies.com/how-to/content/how-to-quiet-noisy-water-pipes.html

If these methods do not work for you install a water hammer arrester. 

See... https://www.youtube.com/watch?v=2Z0Tb1SdFGk