I sold one of these type of thermometers at hershey 2 years ago for $125. The subject condition and subject matter are everything. Not much of a collector base for insurance signs sso i put yours in the $100-150 range.
That style of thermometer is rare in itself, as you can imagine it wouldnt take much to destroyed it. Not many of these big glass therms surviived. I only see 2 or 3 a year. Ive never seen 2 glass thermometers advertising the the same subject matter. I have seen these thermometers in 3 differnent sizes. I have not seen a 6 ft version before, but know they were made as i have an original sales brochure from the company that made these ROG therms.
Thanks for sharing