As long as you are happy only going to 36F to lager then there's no reason to move away from your fridge. Just buy a temperature controller. I have the Johnson Control A419 and it works very well. It switches from cold to heat control by opening the box with four screws and moving a pin inside. Very easy. You can spend less if you feel comfortable wiring the controller yourself. I don't so I bought a plug and play device. To heat that up in the winter I use a heat wrap that is similar to fermwrap but designs for reptile tanks. It's cheaper and seems more durable than fermwrap or the old brewbelt.