As Bob says the Cedaronics kit is a good price.
If you are DIY able the electrically aware they can be put together quite simply. They work around an STC 1000 £15 ish on ebay. I built mine with fixed sockets instead of trailing ones. One for the cooling, fridge that is, one for heating say a small tube heater. Cedars one have a nice meaty relay I believe. One I made earlier, as they say
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I can recommend the Cedaronics temp controller as I have used it on the last few brews and works very well, Tim @ (Cedaronics) is very helpful if you have any questions.