If you are refering to the Vashon Industries catalog we are selling, There's a mistake in the listing where it says shipping is $4.80 in one place, but shipping charge for the catalog is $3.00. I think that's reasonable. For our other items we generally charge $4.80 for the first item and $2.00 for each additional. This allows us to properly package the items and ship them using either First Class or Priority mail.
The link in my signature is to the "Auctions Browser" at PayloadBay.com. These are rocketry-related items from many vendors. So, you may be looking at someone else's auction listing. I should have included the link to our auctions page: https://www.jonrocket.com/auctions.html.
Some vendors inflate their shipping cost to try to reduce the amount they have to pay to eBay and to make the item appear to be less expensive. As a bidder on eBay, you should always consider the shipping cost when deciding what to bid for the item.