First it was books, then it was fruit, and now it's — paper towels? Amazon could soon be diversifying its growing retail empire to target the kinds of things people frequently buy at warehouse club stores as part of a new "Pantry" service that will launch next year.

Items you don't normally buy online

Citing sources, USA Today says Amazon's in the midst of planning a service that will offer around 2,000 items people typically buy at shopping clubs like Costco and Sam's Club. This includes "cleaning supplies, kitchen paper rolls, canned goods like pet food, dry grocery items like cereal and some beverages," USA Today says. Some of these items are expensive to ship, but Amazon might have figured out a way to solve that. It's reportedly charging what amounts to a flat rate for shipping, while requiring that all the products from an order fit inside a box that has both a size and weight limit. Presumably both of those things will be calculated as users shop, or before the order is placed.

Amazon already has a service called Subscribe & Save that offers shoppers a way to get some household goods on a rolling subscription, and at a discount. It also sells nonperishable grocery items, as well as fresh and frozen items through its Amazon Fresh service. However, the company's been a slow mover when it comes to Fresh, which only launched in its third city — San Francisco — this week, some six years after its initial debut in Seattle. USA Today says the new Pantry business, which Amazon is declining to talk about, already has a boss, as well as set fulfillment centers that will stock all those potentially big items.