Just a couple of things that may help (and only my opinion--other sellers would have other ways of dealing with this). When someone requests pick-up for something that can be easily and inexpensively posted, add them to your block list before they have the chance to buy. These buyers have always been the ones that have kept me waiting at the location and have wasted oodles my time in messaging, all over $4.55 postage (this was before I had 'Free' post). Once, a buyer wanted to drive to my house in the Blue Mountains from Western Sydney. I pointed out that the return trip would cost more than $4.55 in petrol, but they STILL insisted. I blocked them from purchase--it's just not worth the hassles when a buyer is disrespectfully pushing their point and demanding to come to your house/workplace.
If she had already bought, then requested pick-up, you probably wanted to be accommodating to the buyer even though it was an unrealistic request on her behalf (it's an example of how the eBay feedback system inadvertantly extorts 'bend over backwards' behaviour from sellers). When she requested posting the item, you could have paid for a registered post label out of your own pocket (so you had proof of post), and cut your losses on this one (to save yourself further worry).
If you ever get any inkling at all that a buyer will be difficult from an initial message, block them before replying politely to their message:
1) Demanding, strange, overy picky or rude enquiry
2) Add buyer to blocked bidders list
3) Very polite response which puts them off from buying the item
It is worthwhile responding to their enquiry because, from experience, they will just keep pestering you anyway! When eBay once explained to me that I can add 5000 IDs to the BBL, I thought it was ludicrous. Who would want to block so many potential customers? The fact is that some customers are more trouble and stress than the money is worth...I have learned the hard way.
