The "re-purposers" are getting more open about it...
http://sfbay.craigslist.org/eby/wan/4602961929.html
Here is the reply I sent them...
I AM a collector and would like to ask that if folks direct OLD treadles/machines/cabinets to you, PLEASE shoot me an email with a couple of pics before you do any cutting or modifying of potentially rare machines and or parts.
I would pay you a good price for parts and or machines that are significant.
I have already seen "re-purposed" components that were part of a very rare 1865 machine that are now virtually worthless as an original, and only worth market value as art.