I remember a TV show a couple of years back where someone did an experiment. They set up a stall selling muffins for 1 pound (they were in england...) and didn't have much success selling the muffins.
The next day, they advertised their muffins as 2 pounds, but onsale for half price, and they started selling like crazy
another day they set the price at 2 pounds with a buy 1 get one free, and again they sold like crazy
another day 2 pound muffins but 2 for the price of 1... more sales...
What they proved was that people will buy stuff if they think they are getting a good deal. They were still selling their muffins at 1 pound each, but the different way of advertising their price affected peoples thinking.