With the exception of the #1, all of the other material appears to be used copies of relatively modern issues so the lot's value is mainly linked to the #1. You've got time to ask the seller for a scan of the back and I'd recommend that you do so if you're seriously contemplating a bid.
Here's a larger view of the face of the stamp -- the upper right corner appears to have issues and a scan of the back should help clarify that.
