I think it was a pretty clear question, what is your top earning photo? It wasn't aimed at everybody. Not what is your rate for shooting a portrait or wedding as that would be a different and valid question.
I have two images in particular that have done very well in nature photography, one earning more than $20,000 in its lifetime, the other somewhere in the neighbourhood of $50,000. My largest single stock sale ever was for $28,500 (several images, not just one). Ahhh, the good ol' days...doubt we'll ever see those kinds of numbers again in stock.
