Much like what "Magic Secrets Revealed" did to the illusion industry, this site can do to the calibration industry. This site contains several commonly calibrated devices, and how you can do it on the cheap. They mostly have you building IC regulated circuits that output exact voltage, resistance (easy one), and other sources. An argument can be made that those calibration devices need calibration certifications. But, I ask, who certifies calibration companies?
Cabe