You have 12 items listed with good descriptions. Put an ad in the SMH with the same description and see what it costs you.

3 of your listings are listed in 2 categories. You pay for the second category each time they relist, they aren't part of the free allocation. So if they relist 3 times, you will be paying 12 lots of insertion fees.

A couple of your listings you say they are advertised elsewhere, you can't do that. If you are going to list them on eBay, they can't be listed elsewhere.

Your Rick Amor Lithograph, you specify that you will only post if they pay via direct deposit. You can't do that either. If people want to pay via PayPal, that is their choice. You can't turn around and say no, I won't post it because you paid via PayPal. Quickest way to get a negative feedback.

If someone wants something posted and you want to add $10 for the packaging (a bit excessive IMO but it's your call), then you add that onto the postage charge when you send the invoice. You can't put the postage at say $13 in the invoice and then expect the buyer to tack an extra $10 onto it. They only pay what's in the invoice.

You need to read the terms and conditions.