If it ships from Amazon, you can still run the risk that you get a counterfeit item since Amazon will co-mingle the inventory. Safer to only buy from the seller and is shipped by the seller.
Good point! But it's very rare to see Seller shipping the product, as Amazon likes to control the inventory itself. Also, I believe Amazon encourages sellers to ship the products to their warehouses for faster delivery to customers, and they'd cover all the costs within their 15% fees.