I'm surprised you haven't received a bundle of responses to this inquiry, but I'll tell you some of the sources I use or have used.
I use Rieger cane and you can get that from a number of suppliers, including Miller Marketing and NJN Bassoon Products. I'm sure there are others since it is a fairly popular cane. Danzi cane is also popular; I like it and find its a little brighter sounding than the Rieger and I have to work a bit harder to "get it right.". Again, Miller Marketing carries it, as does Tony Romano at All Bassoon Cane. And, again, I'm sure there are other dealers who carry it.
Tony Romano (www.allbassooncane.com) carries cane from perhaps the largest selection of growers and is very nice to work with. His sample packs provide an opportunity to try cane from several growers. Tony also took over the graded bassoon cane operation that Bill Roscoe had for many years, and although I don't know what kind of cane is used for the graded stock, I used it for many years when Bill sold it; hardness #9 was always my favorite.
Finally, Justin Miller has a hardness comparison chart on his site and you can get an idea of the relative hardness of several of the more popular canes. Of course, hardness doesn't tell the whole story. How its gouged, profiled, and what shaper tip you use will have a big impact on how the cane responds, not to mention your bocal and instrument.
I hope some of this helps.
Gene Carter, Owner