Yes they have.
There were some old posts (maybe not on this forum) about the product used in the factories to coat the hair.
You could only get it in large quantities and it cost about $200.
Suggestions were floated about a few people getting together to buy it and then divide it up amongst them.

I'll see if I can search & find the info, or maybe some one else will recall it and point you in the right direction.

This isn't exactly what I was thinking about, but may be of interest:

http://www.wigoil.com/