Wanna hear your thoughts on this.

My opinion has always been that if you're the first to email for an item, you're first to get it. And if the someone else comes along, check whether the first person for sure wants it.

So I was emailing this lady back and forth for an item on cl. We set up a date and time for later this week for me to come pick it up. I told her I lived kind of far so that was most convenient for me. Great, all planned out.
She emailed me today and said "someone picked it up today. Good luck with your search"
I'm pissed! We had it all planned out! I think she should have emailed me and said hey someone else wants to pick it up today- could you come earlier?
I could have made it work if I had known she was still actively selling it! Geez.
I responded and told her I didn't think it was very considerate since we had set up a time and sent at least four emails back and forth.

But maybe I'm wrong?! What do you consider cl etiquette, if anything?