Best Buy, Target, Wal-Mart, Amazon and everyone else sells it too. So I don't see your point.
The difference here is the margins for the third party outfit. The food industry allots resellers wide margins for resale.
Apple offers slim to no margins for third party resellers. As an example, when the iPad mini retailed for $329.99, they were being sold to big players like Target, Best Buy etc for roughly $300. The cellular models are sold at no available margin to the retailer, but for those that have partnerships with the carriers receive a bounty for the activation.
I worked at Best Buy for many years. I can tell you that Best Buy made almost nothing ($10 or less) on iPads. The money was made a bit more on the accessories and especially the service plans. For the little margin the store would make on an iPad, they'd go out of business very quickly if that's all they sold.
I'm talking about COKE everybody, not apple. Coke doesn't sell their product for $1-$2 /liter. Walmart, Walgreens, Kroger etc. do.