Adrian,
Welcome! Very nice work!
Based on your more standard sizes,rectangular-ish and a starting point of $23, I would say you are low, for the quality you present. I think I might suggest that you start with $27 to $32 or so,on your classic sized images and then using that price/square inch,price your Pano's.
People buying here,generally aren't bargin hunters,they would go elsewhere...........
As I always say, "I'd rather not sell something at a higher price,than not sell something at a lower price!"
Rich
