Hearing Aid Salesman

A man realized he needed to purchase a hearing aid, but didn’t want to spend a lot of money. “How much do they cost?” he asked the salesman.
“Anything from $2 to $2,000.”
“Can I see the $2 model?” said the customer.
The salesman put the device around the man’s neck, and said: “You just stick this button in your ear and run this little string down into the back of your shirt.”
“How does it work?” asked the customer.
“For $2, it doesn’t work,” said the salesman. “But when people see it on you, they’ll talk louder.”