Assuming this supplier is the only source for the product, then there are a few things that might be in play here.
1. The online seller/s also has a bricks and mortar store as well, that is how they are sourcing the stock.
2. Non-genuine items being sold.
3. Sourced through surplus sales
If you find a product such as this, I would bring the online listing to the attention of the supplier and ask for clarification of their online sales policy.