Check out a varitey of studios in your area. Ideally, you'll find someone who competes professionally and does well. Avoid any place that tries to push you into signing a contract to buy tons of lessons within your first couple visits to the studio.
If you're really serious, you should try and do 2 private lessons a week, and 1 to 2 groups. At a minimum, you should do one lesson a week. If the studio your with has practice parties, go to them and dance with as many people as possible.
Moneywise? Depends on the area and type of studio. Franchise studios (like Fred Astaire and Arthur Murray) tend to charge a little more, but you may find that you like the instructor and will pay the extra amount. I hesitate to give you dollar figures because they can really vary, but I would say an independent studio instructor would charge between 60 to 90 for a 45 to 60 minute lesson. A franchise probably charges 90 to 150 for a 45 minute lesson.
Regardless of where you go, you can expect to do dances like waltz, foxtrot, tango, rumba, cha cha, swing. The world of ballroom has an international style and an American style. Within each of those divisions, you have what we call standard/smooth (international/american) and latin/rythhm (internation/american).
Check out the "Learn The Dances" section of this website to see the breakdown of the differnt styles.
Good luck
