Sous vide is a type of cooking in which you put food in a vacuum-sealed bag (the name is French for "under vacuum") and cook it in a temperature-controlled, circulating water bath. The result is precisely cooked food with consistent results, like this steak.
You use following appliances to control the water bath in which you sous vide.
Anova Precision Cooker Bluetooth + Wi-Fi is an immersion circulator: you attach the device to a pot of water, and it simultaneously heats and circulates the water. The Anova connects to an app so you can control the temperature or follow recipe guides. But Wi-Fi isn't essential if you want to use the Anova -- there are also controls right on the unit. The Anova Precision Cooker Bluetooth + Wi-Fi costs $199 (roughly £150/AU$265).
At CES 2017, Anova announced they would make a smaller, $99 (£75/AU$130) version of the Anova Precision Cooker called the Anova Nano. The company originally announced a summer 2017 release date, but it's not yet available.
Anova also introduced the $299 (about £225/AU$995) Anova Pro at CES 2017. The control panel will be a full-color touchscreen that will let you access sous vide instructions, controls and guides that are similar to what you'd find in the Anova app. The company has yet to release this immersion circulator.
Most immersion circulators clip to the side of your container. The Joule immersion circulator ($179/$199, which converts to roughly £135/£150 or AU$135/AU$265) has a strong magnet on the bottom along with a clip option so you can put the device right in the middle of your water bath.
Nomiku recently added meal delivery and a scan-to-cook feature to the third generation of its WiFi Nomiku. Nomiku's new cooker can read Radio Frequency Identification (RFID) tags on frozen, packaged food that the company will send to you as part of the Nomiku Sous Chef Meal program. The tags contain information about how long and at what water temperature your food needs to cook. You wave the package in front of the device, and it will read the RFID tag and automatically start heating the water according to the information in the tag.
Some sous vide machines, such as this one called Mellow, are made up of a container for the water bath and a heating element in its base to bring the water to the right temperature. The $400 Mellow countertop sous vide machine (roughly £300/AU$530) also includes a built-in refrigeration element lets you keep your food in cold water until you're ready for the Mellow to start cooking. This lets you schedule the exact time you want your food to be ready without worrying about it sitting in tepid water all day.
The Oliso SmartHub & Top consists of an induction-powered base that heats the water in the SmartTop, the vessel that fits on top of the base. The SmartHub can also be used as a standalone induction cooktop. The Oliso system costs $500 (about £380/AU$660).
The Tasty One Top is a $149 (£110/AU$200) Bluetooth-enabled induction countertop burner designed to help you cook the recipes you see from Buzzfeed's Tasty cooking videos. It comes with a temperature probe to sous vide.
Even large appliances are getting in on sous vide. GE's Cafe series electric slide-in stoves with induction cooktops come with a Bluetooth-connected temperature probe that connects to your smartphone or tablet so you can control cooktop temperatures down to the degree. (This is same approach used by the Paragon Induction Cooktop, developed by GE's "FirstBuild" microfactory/maker space in Louisville, Kentucky.) The combination of the induction burners and the connected temperature probe means you can sous vide on your stovetop without needing to buy an additional small appliance.