I don't feel the OP was in the wrong. It was a semi complicated situation that didn't work out. Buyer got called out. It's haggling like poker. Big deal.
I have done similar a couple times with my CL transactions with people who just don't know how to haggle fairly and respectfully. I'll put in details from one transaction to clarify.
Posted a firm price ($175-bass cab), which is below market price ($200-225) as I want it to sell sooner than later, buyer still shoots a quasi reasonable offer via email ($150). I accept and we set a meeting time based on his schedule (2pm). Buyer shows up late (2:40) and spends an inordinate amount of time (15 minutes) testing out the (accurately described) item--which now is wasting my time as I have errands to run on my day off. When asked if the buyer want's to take the item home, he then shoots a low ball offer ($100), strictly just to do so and used 'driving through traffic' as the excuse. Knowing he drove from 10 minutes away, I decline the very poor counter offer and ask the buyer to leave since we can't close on our previously agreed fair price. In this case, the buyer backtracked and gave me his original offer. A couple other times the buyers were shell shocked that I just didn't cave like the Wal-mart returns counter they took me for.