As of May 2015, Wal-Mart does sell peppermint oil, but it is only available online at Walmart.com. Inventory may vary, but Wal-Mart carries the Nature's Bounty Earthly Elements Aromatherapy peppermint essential oil, which is suited for use in home vaporizers or diffusers.
Because peppermint oil is not stocked on shelves in physical Wal-Mart stores, it is also not available for store pickup. Wal-Mart does offer several shipping options and speeds via Walmart.com. Other brands of essential peppermint oil are sold via the Wal-Mart website, but these orders are fulfilled by third-party manufacturers and are also only eligible for home shipping.