1. Once a thing has been free you cannot charge for it without a significant brand or improvement (e.g. no-spy public wifi)
2. The more expensive a thing gets, the more expensive we expect it to get. Discounts are then counterproductive.
3. Brands and sales do not go together.
4. Charging for a thing makes it seem better. Often the less you charge, you find you cannot give it away.
5. The less you charge for a thing the more aggravated a customer gets over minor variations in price. So charge one price if possible (eg McDonald's coffee $1 for any size).