I bought a wheelset on Craigslist recently. I know for certain the wheels are nearly new. However, I'm coming to believe that the wheels were machine-built and not hand-built. After about 200 miles of riding, I've already had to true a couple of wobbles out of the rear wheel. When I went to true the latest wobble, I found a spoke that had almost no tension at all.
I want to prevent further problems, so I assume I should bring the wheel to my LBS and have it retensioned? How much should this cost?