I don't think you really can warn other sellers, certainly not by simply giving bad bidders a big green dot with negative feedback.
Sellers aren't going to look up potential bidders, there are millions of them, they would only look up people who have already bid and by then your warning is too late really, in a lot of ways.
Surely it would be better to just go through the set procedure and start a non payment dispute. If the person doesn't pay they will get a strike against their name and if they collect a couple of strikes, they will find their bids blocked by some sellers (or so the theory goes).
That's your best way to help other sellers but your main priority is to look after your own sales here, this woman is being unfair.
You need to do a couple of things immediately.
*You need to open a dispute against this woman, she's a menace & a bit of a liar & she is stringing you along. I would say she sort of fancies buying the items, but she isn't committed to paying. It sounds as if you have waited about a month, that is far too long, you've been too lenient. I am not trying to be rude, I have been there and done that with buyers myself in the past but I wouldn't now.
* Oh and don't bother contacting her or mentioning a dispute, just do it. You know if you contact her she will just launch into another promise or beg for more time.
* Block her so she can't bid on any more of your things.
* Do not give her any feedback at all. If by chance she pays after you start a dispute and then gives you neg feedback, saying you are unreasonable or whatever, just answer underneath & explain she had a month, didn't pay till dispute was opened.
