I'm not going to offer direction, just offer info on what you're getting into price-wise.
My first pair of shoes with suede soles cost me $50; introductory shoes still cost about that. Solid black, 1" heels, found by searching for "ballroom dance shoes" on google maps
Group classes are usually $5-$15 and teach you steps, but usually don't teach you how to lead them. Don't discount footwork
Private lessons are usually $50-$150 and teach steps, posture, frame, basic choreography and floorcraft. Rental of an air-conditioned, maintained floor is included in that price.
Coachings are $50-$??? and teach minute mechanics, choreography, or a combination.
"Team matches" (small competitions between local studios) can be as inexpensive as $15 a heat ($15 a dance)
The only collegiate competition I've done was $45 a person, as many dances as you want. This was all amateur partners
Adult amateur competitions can be $70 a person via USA Dance
Professional/Amateur competitions can cost $1000 or more. It's a lot more, but it takes YEARS for an amateur guy to lead correctly and YEARS for an amateur woman to follow correctly, so most people compete this way. This is done with the person with which you take private lessons.
Non-team match competition estimated prices don't include airfare/hotel/food if they are elsewhere.
I'm not going to post my salary, even with a pseudonym, but will state my career: I'm a software developer. Most other guys I've met who stick with it are the same, or doctors, lawyers, engineers, accountants... all middle/upper-middle class professionals who need an outlet for art & sport. Same with the women involved who stick with it.