I used the instructions from http://www.rushlanepoultry.com/cooler_incubators_page.htm . I found them very through and easy to understand. Print off the diagram for you wiring. You CAN do this. Just take your time and follow the instructions. My cost was a little less than $40. I used a camping fan that I already had with fresh batteries. (Home Depot has them). I doubt I will be hatching a lot of chicks and this way I can re-purpose parts when not needed. I have a 53 qt marine cooler (that I purchased from Big Lots for $29), 2- 25w bulbs, Lower Thermostat for Hot Water Heater, Christmas light extension cord, glass for lid $0 from auto glass shop, microfiber cloth for humidity.
Instead of opening the big lid for turning and maintenance I have taped the top of the glass as a hinge for easy access. My lid is so tight that I was afraid that it would scramble little cells that are forming every time I opened it and closed it.