Rare And Collectible Stamps? Right.

Sometimes, the combined shipping is only available through certain Ebay sites.
I had instances where I needed to log on to the UK site to get the combined shipping from a UK seller. It was not available through the Dutch site.

When I see the 'seller doesn't offer combined shipping' nonsense I use the 'contact the seller' option to request a combined invoice.

Except that the seller can't see "Buy It Now" items added to the cart. The seller only knows of the winning auction items. So I can't put 10 items in my cart and then ask for a combined invoice. (edit: I can attempt to request a total for the combined invoice but get the erroneous error quoted above).

Sometimes I get the message "You cannot request a combined invoice because the seller has already offered a discount on one or more of these items." So because one of the items was on sale and I got a ten percent discount on a $2 item, I saved twenty cents on my order but because of that I have to pay $10 total postage since I can't combine shipping? Nah.

Agreed, just use the Contact Seller option. If they can't provide the combined invoice, the seller sometimes says just pay the whole thing and they will reimburse. I can't remember a time when the seller didn't provide a refund of the excessive postage.

If the seller refuses to refund excess postage and causes shenanigans, it will cost them on their feedback. If the seller already has low feedback, then it is buyer beware.

Sometimes when I contact the sellers it turns out that eBay added terms that the sellers never intended. It mostly happens with shipment fees, like fees much higher than what the seller intended, or getting shipment fees when the seller promised free shipment. I concluded that it's often useful to contact the seller.

Ebay is so broken these days....

I have contacted him twice, but no reply. He seems to be unwilling to solve the issue, so @Rob Roy: probably I have to open a dispute at eBay customer service. He has 100% positive feedback.

This is the case:

@Rob Roy,

How did you come to the conclusion you did business with the same seller?

The original post links to a seller from Limassol. The post with the table appears to be a Dutch seller that remains unidentified.

I didn't mean it was the same seller. My example was to show how I resolved my problem with "my seller", who was very cooperative.
If there are sellers that want to cancel a deal by ignoring the buyer, I feel that eBay's dispute might be a logical choice to resolve it.

Got it: bought from one seller that was the same for your items and not four items from the same seller as OP.

I got a new invoice and approved it. I don't know why he had to wait so long. Probably a younger buyer would have paid the shipping cost he first demanded without arguing.

4 euros for the postage is fine. There are about 64 stamps some having margins and some being a little bigger than on average. We know that an A4 sheet weights 5 grams (paper 80 g/m2). These all are mint stamps having original glue on them. Stamp paper is thicker than copy paper, probably 120 g/m2, so those stamps can weight about 7-8 grams. An envelope (depending on the size) weights about 3-6 grams.

The stamps well packed weight over 20 grams, so the postage will be at least 3,60 € according to his table. I don't know what the postage prices are in Netherlands...

The rate for international mail is € 1.65 per 'counted' weight step - there is a strange jump from 3 to 5.
20-50 grammes is weight step 2: i.e., € 3.30.