I am afraid that you are "flogging a dead horse".

This topic and situation has been around for a long time now, and although if you ask any seller about it they will not agree with it, there is nothing that you can do to change it.   

You must make sure that you know your selling costs, and incorporate those costs into your item or suffer the loss.

We do not include post in very many of our items, (unless we have a reason to do so) the buyer nearly always pays for post on top of the purchase price and we pad the item to make sure that the % taken by eBay is not out of our pocket.    

Their fee is shown on the details in the "sale" so you can see very clearly how much you have paid to them.  

We are also trying to prop up our pensions as well as you, so understand where you are coming from.  And many other sellers are in the same boat. 

Sorry that you had this bad experience on this particular piece, wishing you many sales and good luck going forward.