It goes like this:
The randy old millionaire approaches the ravishing beauty and asks "would you sleep with me for one million dollars?"
After a minute to consider the proposition, she answers "Sure."
He then asks her "would you sleep with me for fifty dollars?"
She angrily replies "What kind of girl do you think I am?"
"We've already established that my dear. Now we're haggling price."
Well you can do a lot more with a million bucks rather than fifty.