You can replicate a real test, but it requires considerable effort: First, you need someone capable of imitating a trained polygrapher. The simplest option is

You can replicate a real test, but it requires considerable effort: First, you need someone capable of imitating a trained polygrapher. The simplest option is to hire one, but from what I know of polygraphy I'm pretty sure that a magician could do the job with a few hours study. Second, you need an accurate simulation of real polygraphy equipment. Again, you can just pay for a test, or you can rig something up with a galvanometer, heart rate monitor, and spirometer. Thirdly, as you said, you see to have "something riding on it." Hand a trusted confidant a quarter of your monthly income and tell them to give it to a charity antithetical to your beliefs if you fail the test.