You never should feel that a diet is something you should pay for. All diets succeed when you eat fewer calories. If it's a matter of moving more (exercise), you have to increase physical activity a LOT to keep up with an increase in calories.
Weight Watchers is a balanced diet that charges you money - because you use their support meetings and their weigh-ins.It works for a lot of people. However, there are many diets that are essentially like WW in that you trim your caloric intake - the goal setting and 'staying on track' you can do yourself or with the support of friends, in person or online.
Amazon is one place where you can see all the diet books - explaining all the diets - an amazing number of diets! If you want to try one, you can even ask your local library to find the book for you - that's a very low-cost way to find out all you want to know without spending a penny.