Lowest return but least expensive in a small market. 100 phone calls equals about 1,000 mailings. Better control of the questioning and more detailed collection of information. Next lowest in cost. You can show the product or service.
Customer can sample the product.
Products can be compared to competition. This is the best method for finding why customers do what they do. Here are a couple of things you can do to find out about your customer base. Check license plates in your parking lot. Here in Montana, the numbering on license plates tell what county the car is from.