The supplier's worldwide shipping cost is 2.50$ +1.50 for each additional product in the same order. I would use help understanding how to set that up on my account.
Coming from a Spocket representative:I am not certain if Shopify is able to support incremental shipping charges. I would suggest reaching out to them directly to check this possibility. As this is more directly requires Shopify knowledge.
I don't see any extra space to add another value (1.50$) so if someone from overseas orders multiple products at once and only gets charged 2.50$ in total, then I would be the one that needs to pay out of pocket for each additional order.