Once your Money Machine works without you, you can turn it on and watch it print money. It can run while you are on vacation, at your children's athletic events, or on the golf course.

The problem with tipping at a self-checkout machine is there's no proof the money goes to an employee, Wall Street Journal reporter Rachel Wolfe told CBS News.

After spending about $5,000 on two refurbished machines, Gram started to see the money roll in, claiming he made more than $300,000 just last year from 25 machines.