I can understand and accept high shipping prices if it covers the seller in a dispute (paypal/ebay needs tracking number to prove it was sent)... so if there is no cheaper shipping amount for a trackable package (to cover themselves), no matter how tiny the object is, it isn't their fault.
If you find someone who is willing to take the risk and post something at a cheaper rate that doesn't cover them if the buyer claims they never got it (or it actually gets lost in the mail), then that's great. But to be fair, if someone has been burnt before by doing that, they aren't going to offer cheaper shipping if it leaves them vulnerable for losing a paypal dispute.

Shop around first, if it is possible, and find someone who either doesn't know or doesn't care that their cheaper postage rate won't cover them if the item doesn't arrive (or the buyer wants to get the item for free by claiming it never arrived).
It's unfortunate that this happens, but until such time Ebay forces all items to be shipped by the higher rate (to prevent all those costly disputes), take advantage of those who offer cheaper, unregistered shipping.