It might have been worth swallowing your pride and saying “Well, how about $900, then?” Or even going the full $1000. It’s ‘only’ £30/£60 more. I mean, she was spurning the certainty of an okay deal for an only slightly better possible one … so she would probably have gone for $900. It might even have been a bargaining attempt on her part to extract more from you.
I remember two car incidents, both selling, when similar things have happened to me. One creep, having agreed to pay £1300 for a Volkswagen van, after I picked him up with a friend to drive to his house where we would complete the deal, started mumbling about a ‘noise’ he had heard, his friend corroberated this, and I was beaten down to £1100 – I was desperate as I had a ticket back to Portugal that day. Another time, another van, the guy who was buying, as he counted out his money, ‘discovered’ he was somewhat short of readies.
Again, I had a deadline … he offered his old wreck of a vehicle in part exchange … I accepted the money he had. Even more annoyingly, we bumped into him a couple of years later in Gibraltar, driving our old van, where he invited me into a restaurant for a coffee, which I ended up paying for!!!