I remember looking up the profit margin on printer cables (the old Parallel type) when I worked at Office_____. I don’t remember the exact markup, but it was more than 100%.
It’s far more than 100% now. When I held my glorious Staples retail job in 2003, the $30 gold-plated 6-foot Belkin USB cable cost the store about $4. (This left plenty of profit for Belkin as well.)