Both the question and the answer are entirely subjective. How much the pipe has of qualities of value to you determine how much better or worse to you it is, and thus what you are willing to pay for it. For some, it may be its age or rarity or some uncommon marking, for others, it will be the shape of the grain or the finish or the design and execution. It may be little details or it might be global ones, such as how much the pipe fits a certain style you seek for your collection. Most of us do not have the luxury of trying the pipe out before buying it or even seeing it first in our hands, but some expensive pipes smoke poorly and some cheap pipes may smoke well. Keep in mind that most of the traits above will have little or no bearing really on how the pipe actually smokes--- blindfold a guy and stick a $500 pipe in one hand and a $50 pipe in the other and probably most people could not tell which is which, based on the smoking alone. Briar is briar and good and bad briar may turn up anywhere, and the pipe might be an old estate and have a minor blem and be a no-name seconds as a result but otherwise have very fine quality briar and excellent execution and smoke like a dream, but sell for $12. Take away the minor blem, put the maker's famous name on it, and VOILA! You now have a $150 pipe. It is your wallet.