I don't have a source for general sock supply, but my company carries the Injinji and Fox River line of socks.

Injinji are the socks with toes. Fox River in their own words, "is good for the environment, is made in the USA and is a darn good sock..." We haven't got the Fox River line added to our website yet and only a portion of the injinji lines but you can see some what we already have available here: http://cotradeco.com/produc..
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See the manufactuers sites here:
Injinji: http://www.injinji.com/
Fox River: http://www.foxsox.com/

We have an affiliate and wholesale program and would be happy to help get you access to the lines of socks we have available if it would be useful to you. http://cotradeco.com/pages/..
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Or you depending on how big your "sock market" is you might try contacting manufacturers direct to open accounts with the companies you think would be a good fit. I am sure they would be happy to speak with you and give you advice.

I wish I could be of more help, but I thought at least offering two brand options would be better than nobody answering!

Best of luck Bev!

Knee Socks Wholesale Information

You can also create your own socks by placing a custom knee sock order

Socks are Made in the USA

Source: http://www.kneehighsocks.org

Fort Payne, Alabama, calls itself the sock capital of the world and if you check there, you'll find a bunch of sock wholesalers like Baker Hosiery, Alabama Wholesale Socks, Gerald Smith Hosiery and more.