This one uses an electroencephalogram, so it will also be cheap.
From the abstract:
To better characterize the cognitive processes and mechanisms that are associated with deception, wavelet coherence was employed to evaluate functional connectivity between different brain regions. Two groups of subjects were evaluated for this purpose: 32 participants were required to either tell the truth or to lie when facing certain stimuli, and their electroencephalogram signals on 12 electrodes were recorded. The experimental results revealed that deceptive responses elicited greater connectivity strength than truthful responses, particularly in the θ band…
We all know a tool like this could be used for bad purposes. But if it is inexpensive, it may also serve the good as personal computers and the Internet have done to some degree.
I look forward to the day political candidates and people who testify before Congress are required to take lie-detector tests on statements that have significant public impact.
Interpersonal communications will change drastically the day low-cost lie- and mood-detectors are made available.
Better prepare yourself by doing FIML now. Save yourself the embarrassment later.