Exclusively for Prime members, Amazon offers a selection of sample boxes, bundled with 100% back in Amazon credits, as listed below. Plus, all orders receive free shipping. Assuming you'll use the credits, you're essentially getting these sample boxes for free. The deals: Note: Be sure to scroll down to the product description to find a link that'll land on a page of items eligible for credit redemption. Also note these boxes have an estimated shipping time of one to two weeks.