Tim -
I can't tell on my work computer if it's the same banner you're referring to (the background looks the same), but one just sold on ebay for 175 dollars, which I would think is just about right.
Again, it may just be my less than stellar monitor, but it looks like the one you show in your post has some damage along the right side -- if that's true, it could impact the value.
http://www.ebay.com/itm/Rare-1968-De...item256841e495