cant look only at the disparity between $400 and $5,000. I think fault could lie with the client, too. What was the brief about? was it written down what was needed, outcomes of the shoot etc? Sometimes, ppl interpret things differently. To the amateur, he may only think it's about taking good pics with no relation to concept and execution (stated earlier by some bros), whereas the pro has the experience to quote for things he anticipate will be needed.
So, to me (with current avail knowledge), fault lies with the client for being foolish.