It depends on the kind of dancing you want to do and what your goal is. Private lessons are the most expensive, and if you want to compete, they are a necessity. But if you are interested in social dancing, in most communities, there are other options that are much more reasonable. Most studios have group classes that often range from $8-12 a hour and you can also look for inexpensive or free dance classes at the Y, the community rec center, various organized dance groups, and some clubs/bars that have dance lessons early in the evening (most common for salsa and swing dancing).
If you want to dance, you can find a way!