Lowe's, Best Buy and Home Depot all carry a large selection of deep chest freezers. WebstaurantStore also has a good selection of deep chest freezers, but they are restaurant-quality appliances.
Deep chest freezers are economical because every inch can be used for storage. Some chest freezers have automatic defrost, but most must be defrosted manually.
Deep chest freezers have built-in side-wall insulation, so they hold cold temperatures well. They don't require a lot of energy to run because of the insulation, and a freezer without power can keep the contents frozen for up to three days as long as the freezer lid remains closed.