As Melody Johnson and Shirley Lewis enjoyed a relaxing day at the Ritz-Carlton, Half Moon Bay day-spa, they were troubled. They thought it was criminal that many people couldn't afford such an experience. The two women see relaxation not as a luxury but as a crucial, restorative part of life. With that in mind, they decided to create a place where people can afford to experience a full serving of relaxation. Thus, Sacramento's Waterfall Relaxation Center was born. Last year, Johnson and Lewis started with a once-a-month, special event offering therapeutic treatments such as massages, waxes, facials and foot soaks. It started as a market research project, but ended with 300 clients for th