The Six Dollar Man is (just barely) a robot built by Professor Nucleus Von Fission. In a Sesame Street News Flash, Kermit interviews the professor, who describes in detail how his mechanical man was built using parts that only cost him a total of six (presumably U.S.) dollars.
When the contraption is turned on, it has no apparent motor control and procedes to wreck Von Fission's laboratory (to the professor's delight). When Kermit complains that the robot is a failure, the professor asks, "Well, what do you expect for six dollars?"
The concept itself is a spoof of 70s sci-fi television series, The Six Million Dollar Man.