More-over you won't need to be wealthy to have a good time. It' s difficult for you to learn to dance in any modern style if you haven't already been dancing for two or three years in some more social style. If you have to look at your feet when you learn a new step, you are still a beginner. There are many places in most communities to learn social dancing. If you are determined to learn modern dancing NOW, take private lessons, and be prepared to have those lessons continue for more than a year.
Dance is often a body contact activity.
You need not overdress. Ties are not essential dress for men at most dance venues, but a clean shirt is. Running shoes are no better. They might be comfortable to wear, but they grip the floor too much for dancing. You need a shoe with a leather sole that is firm on the floor, but will also slide.