@supiw
If we put ourselves in this other person's shoes for just a moment, we can see that she perceives you and these other eBay sellers as mugs, selling under-priced goods.
You said yourself that you put hundreds of hours effort into making the pieces so why don't you set an asking price closer to what it cost you, personally, to make the thing?
If this were Dragon's Den, they'd be asking you "how much does it cost you to make this? How much profit do you make?" Based on your responses in this thread, they'd probably tell you to stop wasting your own time and do something more profitable instead.
However, you are not trying to run a business and the expression "it's a labour of love" seems to be more appropriate. You do it because you get enjoyment out of it. Fine by me.
However, I think I can infer that you are using eBay because you live somewhere where there are too few customers, with too-small wallets to make a market stall at all viable. Chances are the woman you're complaining about lives in a major metropolitan area with access to a large customer base who aren't short of money and are accustomed to paying handsomely for labour-intensive, exclusive-design products.
Needless to say, rich idiots can't impress other rich idiots using these products unless the "designer" item has its easy-to-see label.
Charge what these things are actually worth and you won't have to block this woman any more because she won't have any profit margin left, after paying delivery, eBay and PayPal fees.