Last few months on eBay range from $100 to $350...
Prices will probably keep edging up too,
especially after the release of the N.A.R. book,
Kashmir's unsmoked cased set of Blue Ribands would command a small fortune I reckon...
I agree with what's been expressed above. I think several variables drive price: condition, shape, and grain (in that order). I have tracked selling prices of Blue Ribands for the last several years and, on average, they sell for between $225 and $275. Prices have increased of late.
At the last Chicago Show, I got lucky and discovered a large trove of Blue Ribands at Iwan Ries that had just come in as a result of a collection acquisition. I bought 5 of them for $700. They were all shapes I didn't have that were in wonderful condition. And they sported beautiful grain. There were considerably more of them for sale but I was uninterested in the shape or the condition wasn't great. A number of people beat me to the punch. There were a couple of unsmoked pieces that sold for $125.
Needless to say, eBay is not a great place to buy if one wants better prices. If you prevail at auction, it is because you are willing to pay top dollar. These days, it seems that everybody is paying attention. Pipes don't seem to slip by unnoticed all that often.
My buying of Blue Ribands has slowed considerably of late. At this point, I'm interested in shapes that I don't have, and I'm interested in better-grained specimens that are in better condition than the ones I have in my collection.
I've pretty much resigned to myself that acquiring a Blue Riband isn't going to happen any time soon. The shapes I admire are typically hotly contested on Ebay. Perhaps bumping into a seller at a show, like Neill did in Chicago, might be my only chance.