Yep, a temperature controller and a fridge or freezer is all you need for fermentation temperature control. Plug the controller into the wall, plug the refrig/freezer into the controller, put the temperature probe from the controller inside refrig/freezer, set the temp on the controller and you're done. They have analog and digital ones, like the ones here:
But you can pick one of these up anywhere online, ebay, other homebrew retailers, etc. And you can definitely lager in one of these.