OK, I looked at the book and it only shows a 5 cent version. This means your's could be the only one known and rarer than the one listed. It could go 700-800, BUT it's in pretty rough condition which then kind of knocks it back down, but I certainly wouldn't take less than the $500 listed for the other one. In the end it's worth whatever a collector is willing to pay.
If you are interested in selling it, PM me and I will give you the collector contact info I have.