Haha, no! Just make it roughly reasonable with your items, and see which country the main buyers of your items are in! The OP should have posted it in the United States.

As long as the Americans think $4 is acceptable, it's fine. Don't think too much about other countries. It's tiring. The shipping fee on eBay can be set to different regions. But it's troublesome to do. Just use a flat shipping fee. They only know how much it costs to use their shipping method!