Why does no one want to accept that they may not have items that people want? Everyone wants to blame some mystical technical glitch. Sometimes its just as simple as no one wants your stuff.
Browsing your inventory, it looks like the contents of my local Goodwill store, but with prices that are 15X higher. Just looking at one of your items at random, a vintage Nautica sweater for $37 shipped. Sure, there were 208 vintage Nautica sweaters sold on E-Bay in the past 60 days, but 93 of those sold for under $20 shipped. So already, about 50% of your competition is much cheaper.
And there are currently 868 vintage Nautica sweaters for sell. So you are only looking at about a 25% sell through every two months. So if you are in the top 50% of pricing and only 25% of E-Bay's inventory moves, you may sit on that item for 8 months.
And oddly, every single sweater listed was listed by someone with an E-Bay store. So any advantage a store might give you over a causal seller, doesn't exist for you. Every store is probably giving the same handling time, the same return policy, probably all top rated sellers. Every advantage negated and cancelled out, because everyone is on a store.
So for that item, you are looking for that one buyer who will pay top dollar, so you are looking for the top dollar buyer. The reality is demand ebbs and flows. If you can't put an item on E-bay and hold it for 6+ months without financial pain, you are in the wrong place to cater to top dollar buyers. Often, you will be catering to an audience of one, and you have to wait for that one to find your item.
I sell vintage collectibles, and I can list rare items from the 1940's and have them sell in a week. The next month, I can list the same items, and they don't sell for 9 months. Ebb and flow. I don't operate on a shoestring budget, so I can afford to have my money tied up for that long. Nearly everything I have ever listed has sold, it's just a matter of how long it took. About the only exceptions to that are books and movies. I've had to haul those things off to Goodwill several times.
There are also two types of buyers out there, and you only seem to cater to one of them, alienating half your market. Some buyers will NEVER make best offers. They hate negotiating and will ignore buy it now. The second type of buyer will only buy of there is a Best Offer. They just will not pay a BIN price. You must price your item close to what the the market will bear, but have enough margin to at least knock 5% off the price if that will land you a sale.
