Bubba, it depends on how many days a week you go. Mine was $125 a month for 2 classes a week plus equipment fees (pads, wraps, gloves, etc).
I'd suggest seeing a class before signing up, so you can get an idea if it is going to be a waste of your time or not. I'd stay away from "flashy" stuff personally, as it is pretty fucking stupid and useless in real life scenarios.
With that said, most popular UFC/Cage Fighting martial arts (Brazillian Jui Jitsu, Muay Thai, etc) are pretty intense and are way
better in terms of actual real world use than something silly like Karate or Tai Kwon Do.
Just please don't just join so you can be some cool bad ass who has something to prove