Hi,
i think a few people know i did used to sell trustone. Not that commercially though and not any more just JoWo nibs now.
I am not saying the stuff shown on ebay is not genuine it may well be and probably is.
But as far as i know there is only one manufacturer and thats rt research in America.
I never bought direct myself from them, but through someone i know who has access, but if you follow the link the current colours are there. They say that only the pliable colours are able to be turned with hand tools, and it is true that most of the colours available are on the pliable pages but i can see many colours i have bought and turned that are on the 1st couple of pages.
I have no idea whether they have the ebay ones at rt research and not shown them but they do seem to update the colour charts regularly regularly.
If they are copies and i say if. They do look different to the rt stuff as they look so different.
Personally i wouldn't buy them, not because i cannot guarantee they are genuine. I just don't like the colour as the ones i use tend to look like the minerals they are sometimes named after, or have gold veins through them. I keep mentioning provenance because i think it is so important to me when i try to market a pen even at a small scale. It appears to be important to customers as well.
I know it is a secretive process to make them but then i think that the metal pen blanks seem to be made in a similar way and i think from a different company. I like the metal ones as well for different reasons and they do sell for me but not loads.
I have sold more of the stone but its the provenance of the material that does it as they have to be more money of course than acrylics.
I don't know where the £4 per blank comes in as i have never bought them that cheap.
I hope this helps.
Pete