Salary
Average Salary: $75,000
Expected Lifetime Earnings: $3,131,100
If you want steady income as a polygrapher, the way to go is with the CIA. After you pass your polygraph training program, you can earn between $60,000 and $94,000 a year (source) and a five-year contract. After five years, if you do a good job, they'll renew your contract. If they don't, you have the skills and experience to take your act on the road to the private sector or law enforcement.
Privately, the average starting salary is just $30,000 a year, but that raises with experience to $75,000 on average (source).
Unfortunately, there's not a lot of job security in the private sector. However, if you get in with a law firm, prosecutor, courthouse, private investigator, or large corporation, you should always find work.
If you work for the FBI or the CIA or are on a company payroll, you'll get health benefits too.