I have a single frame exhibit of the Ohio Farmers Insurance Company. (
http://www.rfrajola.com/Liebson3/Liebson3.htm) I would agree that the price on this one is aggressive (my opinion, anyway) but I think mailed insurance policies are quite an interesting creature.
The Ohio Farmers Insurance Company went on to be the first significant user of window envelopes (so far as I can determine) in the 1870s. There are also several scarce revenue stamped paper items from the company as well (imprinted revenues on the policies).....