See previous answer.
Issue is not the cost but shipping + 50% duty on the total.
Where are you that's subject to 50% duty?
If you have, or get, a Rohloff, then you may as well use the correct screw, whether that's buying replacement or doing what many do and re-use the original.
Likewise a Shimano 11.
If you're tapping an Alfine 8 to make it oil rather than grease lubricated, then any matching grub screw will do, there';s always a bit of clearance under the shell, you'll have to google that and it is of course at your own risk.