how rare is 1969 Glendale Stamps OJ Simpson?
 

I bought this card at a card show quite a while ago, and have been thinking about selling it. But I can't seem to find it for sale anywhere, and don't see any remotely recent sales of this card. For seasoned vintage football collectors out there -- do we have any sense of how rare this card might be? And if anyone is aware of recent sales that I cannot find online, what does it typically go for?

Thanks!