I would like to point out something that most people do not realize about eBay. 90% or so I estimate, of consumer products that are sold on eBay are usually drop shipped from certain companies who fulfill such orders and contracts on behalf of the seller. This allows the seller to keep costs down, since they do not have to pay to have the item shipped to them, and then pay to reship the item to the buyer themselves. The problem is, a huge number of warehouses and "dropshippers" are dishonest, and are the crooks. I have fallen victim to them myself. It is hard to find a reputable supplier. I have found a few, that ship within 24 business hours, have always stood by their products. The problem is, there are not very many out there, but a seller has to start somewhere.
In the case of your seller, I can say from my own similar experience, that she probably did have a supplier, and the supplier probably was a ripoff outfit. She probably didn't refund your payment because she couldn't get a refund from the so called supplier.
It is possible to sell without carrying inventory, however, you must ensure it is a reputable outfit, who's reputation can be vouched for by either other sellers, members, or most importantly the Better Business Bureau. An honest dropshipping outfit will not generally have "dropship" mentioned anywhere in their web address or company name. DO NOT, I REPEAT DO NOT, fall for suppliers like Simplx, or ClubDropShip, while they are reputable, they charge high fees for a crappy service. All they do is link you to other sites that you place the same order with as the buyer placed with you. It works, but you make almost no money on something like that, and most items are still priced higher than what everyone else on ebay sells for.
Either carry the product yourself, or if you do find a supplier you want to try out, place a personal order, and time how long the order takes to arrive, how well it was shipped, and if there are any problems, it is probably a bad idea to use them.
I know of some real legit dropshippers, but I do not want to give away trade secrets that I found on accident after hundreds of hours of searching.
For buyers who are really concerned, if an item listed has a stock photo, one that is used in other people's listings as well, it doesn't hurt to ask the seller if this is shipped from a third party. If it is, beware there may be problems. It's not the sellers fault, the seller just needed to get started somewhere, and happened to pick a bad supplier. People really do make money this way on eBay, but it takes LOTS of hard work and research to get set up properly for it.