I have ordered single units as replacements which came without having to pay extra duties. Buying bulk means you definitely have to pay the duties, and also the fee to the courier company to 'process' your order and delivery. I am out of stock of Ledger Nano S devices and most likely not ordering bulk again, unless I can make it worth while.
Bulk orders are not priority to them, so they sometimes take months to arrive, while the price of bitcoin changes drastically during that time period, which means your profit can disappear completely.
For the end user, its faster and cheaper to just order directly from Ledger now, especially since they added free shipping for small orders to South Africa, and you might not need to pay duties.
Bulk orders you still need to pay for shipping, so that is additional cost for resellers too. The time, expenses, and possibility of losing money means its just better to refer customers to them directly.