I had a clogged main drain pipe. Mr. Rooter came out and unclogged it, but let me know it was going to clog again since all they could do was push through the clog, but not jet the main pipe since we didn't have a "clean out." We got a quote from Mr. Rooter, which seemed high (and was, based on after the fact research), but when the drain clogged a few days later we needed to get the system taken care of, and didn't have time to get other quotes (I tried, but couldn't get anyone else out that day for comparison).
Sometimes a faucet leak can be stopped by replacing the rubber washer at the end of a faucet stem or cartridge. This is a more common repair on older fixtures when things were built to last and designed to be able to be maintained. Other times the whole stem or cartridge needs replacement or the bibb seat deeper back into the fixture needs replacement. That leads to matching up the right components and often times making a trip to the hardware store or plumbing supply house necessary due to the many varieties, makes and models of faucets. My advice is to make sure your Plumber has faucet repair kit on their truck before having them come out to assess the issue.