About a year ago, I bought the Centennial box and two of the discs skipped. I found it again at a shop last week for $200. When I asked about the return policy, the clerk removed the store's plastic and we discovered that it was a sealed copy! I'm ripping it and the first disc has a minor scratch, but I'm keeping my fingers crossed that nothing affects play.
Assuming everything plays okay, I'm ecstatic to finally have such an important, rewarding set. I have to be at around 70-80 CDs of Duke's music and I feel like I am still scratching the surface.