Yes they are the distributors - I did a group buy from them for Dzus fasteners for the HP2 seat for HP2 guys a few years back. You get a variety of types of fasteners and lengths = nonD-ring etc. Important to do your homework first as to the specs you need. You may find some off the shelf similar fasteners at bike shops that are knock offs used for fairings etc that may be cheaper.
I went on the lookout for them and they have similar ones on specifically the BMW 1200 GS and on Honda XR650L, probably the other models too.
Although this might be the best long term solution, I have fixed the problem for now.
My solution? A
Square Peg in a Round Hole 
The flat square nut pulls into the barrel and edges itself into the plastic, preventing itself from turning. There's a convenient little shoulder at the very end of the barrel that prevents it from pulling through.
I'll still have a look at other options, as I'm sure that the quarter turn D-link setup will be a better permanent solution, but this will do for now.