You might be convinced you're on to a sure-fire winner, but not testing your business idea before you launch means you're asking for trouble. Even if response from prospective customers is overwhelmingly positive, you could learn something that enables you to enhance your offer and make selling that little bit easier.
Long before you take serious steps to start a business, ask potential customers their opinions of your products or services. Find out whether they would buy at your prices, and if so, what and when would they buy. Ask them what they like and dislike about your competitors, because this could provide you with important lessons.
Getting pre-launch feedback enables you to make changes (great and small) so that your offer is more closely tailored to market demand. It's easier to make changes before you start up as a result of researching your market, rather than later having to convince people to buy something they don't want, which never works.
The Start-Up Donut online business guide provides further details on simple low cost market research techniques, how to get your market research right, including dealing with good and bad feedback and weighing up your competitors.