I'm with hoosierpipeguy on this one. Beyond the 4 to 500 dollar range you're largely paying more for the maker's aesthetic sensibilities, market hype, autograph, but not for better performance. Myths abound around briar and far be it for me to puncture them. I'll just go with what I've learned from some well respected sources on the craft and materials, and will choose not to believe those myths.
That said, the pleasure that a person gets from owning and using a finely made pipe is where it's at, regardless of what motivates that pleasure.
This mythologizing about briar has been part of the scene since forever. 100 year old wood is the best, 200 year old wood is better than the best, this or that is grain better, etc. The best briar costs hundreds, or thousands of dollars a block, etc. Utter bullshit.
A "perfect" block? Nobody knows until they try to shape it. Once in a long while one does appear, and I'm watching the creation of an amazing pipe from such a block. Nope it's not for me, but the people involved thought I'd find it interesting.
In some ways, too much is made of the briar, and not nearly enough of the chamber geometry and the airway though to the slot, not to mention the shaping of that last inch of the stem. And none of that matters if you have really bad smoking habits.
If you know what you're doing you'll get great smokes from almost any pipe, and if you don't know what you're doing, no pedigree will help you.