The equipment for the home cook is getting better and cheaper.
Mine was very cheap. I just bought a controller for less than twenty bucks, and plugged an old slow cooker into it. It even included the temperature sensor for that price. The only problem with it is that it only reads out in Celsius, but that’s not a big deal (you can fix it by spending $35 instead). For bigger pieces (like the small rib roast I made last night), add an immersion heater for eight bucks (in my case, from Bed, Bath and Beyond) and use an insulated cooler. The only issue with that is that there’s no circulation, so I had to stir it occasionally to get it evenly up to temp. But it still beats hundreds of bucks for a fancy kitchen machine. And there are DIY guides for building circulators out of an aquarium pump.