Are you looking for shakers or mills?

For pepper you may want a mill because freshly cracked pepper will taste fresher.

For the salt there is no reason to get a mill - it’s sodium chloride. It doesn’t degrade when cracked like a peppercorn would. Salt mills are a gimmick :)

I have a small peppermill for pepper. I’ve probably had a decade but can’t comment on BIFL as I don’t use it heavily.

For salt I have one of those shakers they usually keep chili flakes or parm at a pizza place. Glass body and metal top with big holes. Kosher salt. Had for forever. See no reason it shouldn’t be BIFL unless I break it. Any restaurant supply will sell them.