What is the value of a 1911 Round Rear sight

Hey I found a 1911 Round Rear Sight in my parts bin the other. The one that was on the first colt 1911 pistols all the way up to around serial 60,000 or so.

It's in nice shape and moslty a nice patina. A buddy wants it. What are they worth? I've never seen one to sell to gauge a price that is fair for both us.

Thanks in advance.

The last one I saw For Sale was priced at $100. And that was a couple years ago. I don't know for sure if it sold or not. They are definately hard to come by though.