I am feeling a bit guilty now and what I am going to say now probably isn't good business practise.
I am not the only indie dyer who strives to be as ethical as possible.
I know several who buy from my supplier and care deeply about the origin of their yarn.
If you are concerned about the origin of your yarn, e-mail the dyer first to check where their yarn comes from originally.
You can try e-mailing the big name yarn companies, not sure if you will get an answer but its worth a try.
I think I might start adding the country of origin to all my on-line sales items and add it to the labels (I am sure Heidi can fit it in somewhere -:-)