rk,
Just a couple of other thoughts.
Check your Yellow Pages for Dance Supply shops in your area. Find ones that sell ballroom dance shoes.
Visit the stores. They often know where group classes are happening and/or allow local teachers to place pamphlets/posters advertising group classes.
Now I think you are smart starting with group classes to test the waters to see if it's for you. A couple of things to recognize:
a. group classes teach steps not dancing
b. there is no substitute for private lessons with a good teacher. The light goes on the first time you feel your partner move because of what you did with your body rather than pushing her into position. You'll never develop that in group lessons. As an example we briefly substitute taught a middle-aged couple that got the the bug and have been running around taking every possible workshop they can get too. We took them aside as they have potential and suggested they would be better off studying once a week with a private teacher and reccommended one(not us by the way). They signed up for group lessons with a local teacher who is very popular with groups. They came to our club's beginner practice which my wife & I monitor. They had learned a reverse turn lady outside in tango but were dancing it like an out of control Viennese (the teachers on this forum will know what I'm talking about). They'd learned a step in a group class but it will take private lessons for them to learn it correctly.
If it were me in your situation I'd work to learn all the bronze steps then start working with a private teacher as well. In your visit to the dance shops you can probably find names of independent teachers who will not lock you into a contract.
You'll also want to work with a teacher that teaches legitimate syllabus. You don't want to go to a teacher whose main purpose is to sign you up to enter monthly in-house or circuit competitions where you earn gold ribbons but never learn anything. We had a lady move to our area recently who wanted to take lessons and go to competitions. Over the phone she insisted she was gold level. I took her to a local practice for an evaluation. She didn't know the basic in waltz but she'd been going to a circuit competition for 10 years and winning gold ribbons. She'd been scammed.
Visit some legitimate competitions in your area and find out who the top localfinishers in bronze, silver, gold, etc. are studying with. This will give you a clue to the best teachers in your area. Note: Recognize there is a lot of politics among teachers and students so you'll have to sift through everything.