Makerbot replicator (CTC) Auto Shutdown

I love my Makerbot Replicator clone (CTC), but one of the things this and many similar printers don't have is auto shutdown. In my opinion the auto shutdown option is vital. I do long prints, sometimes over night and I want to go to bed without the worry of my printer running for most of the night after the print has finished. In my search for a solution I found how other people have achieved this, but I thought of what I believe to be a better, simpler solution. And the materials are under $5.