I remember someone posting about this, and having a free moment, and a a yen to be a little different down at the allotment, I have spent some time googling - at last, a UK supplier:
http://ww9.aitsafe.com/cf/add.cfm?userid=B9145685&product=Rubus+leucodermis+NNS00-663&price=4&units=1&return=www.plantpref.co.uk%2Fhtml%2Fr_to_s.html
The latin name is: rubus leucodermis
Whitebark or black raspberry.
I'll let you know if I get around to buying one!
Found this interesting, and have googled a bit. Not sure if they are very prolific, but they do look intriguing, don't they? I am tempted...