I have received email asking me to talk more about the incubator I was putting together. In the picture to the left you can see all the parts I use to build my incubator. The Styrofoam cooler I found on garbage day, but you can pick one up very cheaply. I use this right now to test the whole operation of the incubator. I have a plastic cooler that I will use for my lab. It is much easier to clean and sterilize the plastic.
For the heating I am using an aquarium heater to keep a constant temperature. I use a CPU fan from an old computer to circulate the air over the heater. I power it with the power supply from this old computer. There are many parts that can be used from old electronics. The old computers themselves can be used for programming and hardware builds and you do not need to worry about damaging them.
I found a kitchen cupboard organizer at a department store. This allows me to separate plates, tubes and flasks so the air can circulate around them giving me a stable temperature all around. A multi-meter with temperature measurement was found in a surplus store. This allows me to monitor the temperature without me constantly opening the incubator.
In the picture top right you see the incubator put together with some plates in it. The heater is attached to the cupboard organizer. This keeps it out of the way.