I have an old 50 to 60 foot tall silo built from concrete staves with a metal dome roof. Soemone has offer to buy it nut I don't even know its value.
sometimes, in situations such as these, it's best to ask what will you give me for it? and take whatever they will give providing they transport it. Hey it's money you didn't have before!
You could try contacting a realtor to see if they may have an idea. If not try your county's tax assesment page to see if they have a value attached to your silo. It'll give you a starting point at least. It sounds like an odd offer, but you never know.
sorry to say nothing if you want it removed you will have to pay somebody to take it. thats if even they want it, good luck