I think a lot depends on what you are selling and at what price.

This scenario of postage being higher than item price does give a buyer pause. This doesn't just happen on ebay. I recently had a small metal photo made, it was on special for $3. Postage added another $12.95.

The crucial factor  when this happens will be if it is an item that isn't readily available in stores for much less. In my case, $16 was still a good price.

There are ways around this. First way is to offer the item with 'free postage', so buyers don't see the breakdown.

Another way might be to offer combined postage so buyers feel they are making a bit of a saving if they buy 2 or more items.

Even on other sales sites, postage will still have to be paid, although admittedly on marketplace you might sell locally where someone wants to pick up, so the postage component doesn't come into it. But even there, a lot of people are not happy to travel far for a cheap item and some people just feel more comfortable paying for postage. It's anonymous and it is easier.

Another way is to have combined postage so if a person buys 2 or more items, they feel as if they are making a bit of a saving.