Question for Ebay sellers out there

[Horse with no Name]

I am curious.
I have had a hard time with NPB. A really difficult time, especially lately.
I find that they most often occur with very low number of feedbacks.
So the latest one. Used "Buy It Now".
My auction terms are pay within 3 days via Paypal.
So after 3 days, no response whatsoever, I emailed this buyer.
No response.
5 days, emailed, no response.
7 days, emailed, no repsonse.
Today is now the 9th day post auction. I filed a NPB dispute.
I then check this buyers feedback. It appears she bought AND paid for the exact same book 2 days ago from another seller.:wtf:
I have 100% feedback--and also very good feedback regarding fast shipping, etc. so it wasn't that someone else had a better feedback rating.
Indeed, the person she purchased from had a 97%.
So anyway...when I saw this purchase feedback, I left negative feedback and decided that I didn't want to deal with this buyer at all, but since you have to wait for them to respond, my hands were tied.
She paid for the item tonight. I refunded her money then proceeded to close the dispute console.
But I am curious. How do you handle these types of situations?
A couple of times I have had buyers lead me down this path and gave them multiple chances to pay for an item they decided they really didn't want, then they either don't leave feedback or want to return the item saying it wasn't as described--or simply never pay for the item. Personally, I don't need the grief.