Wait a minute- pipe tobacco marketing? What's that? No, seriously, if marketing had anything to do with it, Captain Black would be perpetually sold out, chased by a rabid pack of crazy pipe smokers. From what I have seen, shortages are driven by two factors: Low production (e.g Esoterica blends, which are made by only a few employees of a tiny company), and reputation. Reputation is the tricky part. Whether by word of mouth or through forums and the like, people get wind that a particular blend is mighty tasty. Then, everyone decides they need to try it. Then it is sold out everywhere. Then, when it becomes available, the people who liked it to begin with stockpile as much as they can get their hands on. The thing is, reputation will wax and wane. Two years ago, Gawith Full Virginia Flake was very sought after and often sold out. Today, you can find it everywhere. The blend didn't change, it was great and it still is great. What changed was people's perception of it. It is no longer hailed as THE straight Virginia blend.