...rough crowd here Lennie, I shoulda warned ya...
I'm sure Len will be taking all this consensus in with a fair mind.
That said, he did take the time to develop, test, and manufacture the sprockets (and a few other well sorted add-ons), and he is in Australia.
I"m sure the price has little to do with the bike brand.
I've had guys who say they work in machine shops and tell me they could make my barbacks for 1/3rd of what I charge for them, but that's like saying one could make a clay pot dirt cheap (pun) if they had a throwing wheel and kiln.
I won't make a prediction, but I bet he'll be more than glad to do a group buy if there is true interest.