Don't forget that Dukes we're not the only bikes to use these carbs, so they should be available from breakers yards etcetera.
Yam XTZ750 definitely and I think the TDM750/850 has them as well.....(the Super Tenere does.....is that a TDM or XTZ?) Allens Performance should also have them in stock. I have a pair of plain ones, but I am hanging on to them for the time being in case I remove my carb heater hoses.
TDM is a parallel twin commuter bike, not a giant trailie like the Super Tenere. When I drilled the pilot mixture screw out of my Mikuni carb, I replaced it with one from a TDM. It wasn't identical but where it did differ, it was larger. So I was able to turn it down to match the other one.
Info on Yams which have the same carbs, it seems..........the last link appears to be the best one if you scroll down....... Super Tenere Network - STN - Topic: Mikuni BDST 38 Carb Part list (1/1) Persnikity 94 YZF750R and Mikuni BDST 83 Carbs! - Bike Chat Forums YZF 750/1000 carb on a FZR 1000 - Yamaha Forum : Your Yamaha Motor Products Community & Resource Carpe TDM :: View topic - Interchangeable bits and pieces
Some of the Yams are different although they will fit - i.e. some have only 2 fixings instead of 4 and some have no drain facility and 'top' overflow outlets so no overflow outlet provision cast into lower face of bowl. Latter is no big deal though as despite overflow system, fuel still often decides to drain into inlet port and onto sump instead.