They advertised a video package to help pilots get their licenses and instrument ratings. They ran two test of an ad in magazines in two parts of the country. Which one do you think would pull the most customers. The higher priced course pulled more customers than the lower price. The customers felt there was something wrong to offer it for such a low price.
People are happy to pay the price if they can see the value.
Don't feel compelled to only test price. Remember, people are not shopping exclusively for price they are really looking for benefits that will make their life better is some way. As you can see, knowing your customers can play a large part in the success or failure of your advertising. The better you know them the easier it is to find the message that works and the fewer tests you'll have to do. You can test too much and that's what you'll want to avoid.