Couple makes $30k reselling Trader Joe's "Everything but the Bagel" spice on Amazon

Juston and Kristen Herbert have a good side hustle: they go to Trader Joe's and buy dozens of 'Everything but the Bagel' spice bottles for $2 and then ship them to Amazon's warehouse. They sell the spice at a markup and Amazon does the fulfillment.
From Money:
He loads [the Trader Joe's spice] into boxes while passers-by shop around him. When the cashier asks what he’s doing with all the containers, he says he’s putting them in gift baskets and sending them to family.
It comes out to $141.29 for 71 seasonings. (The Herberts say they try not to be “obnoxious,” so they limit the amount they take.)
Back at home, the couple wraps the items while 6-month-old Kruze sits on the kitchen counter. There are specific pack and prep requirements they have to meet, but it basically works like this: They put an item in a bag, place a bunch of those in a box and send that box to Amazon. Amazon stores those items in a warehouse until an order comes in. Then employees package the item in an Amazon box and ship it to the person.