As of 2015, a good place to find a toaster oven that can be mounted under the cabinet is the Black and Decker Appliances site. The Black and Decker brand offers a variety of toaster ovens and toasters.
The Black and Decker Appliances site allows users to sign up for email alerts on upcoming deals and discounts. The site also offers other types of appliances for the kitchen.
Another good location for purchasing under-the-counter toaster ovens is Target. Items can be purchased online or the store locator can be used to find the nearest retail location. Wal-Mart is an additional location for purchasing toaster ovens that can be mounted.