Its as expensive or more than expensive than cars. IMHO
AND there are a LOT of unethical people in the sport out to rip you off, do your homework and trust no one.
Go to the nearest real karting track and find out what kind of cart classes are popular. Then expect to spend about $5K for a good used Kart that will not be competitive. If you want to win double that number and expect to spend about $200 per race.
If you just want to lap on practice nights then the price goes down a whole bunch but this will be you playing around and I suspect you might get bored with that.
ITs not as cheap as everyone thinks it is to race and win, Its cheaper to buy a used sports car and Autocross for your competition fix.
This is my opinion based on wha tI have been through getting into it. You better be an expert before you dive in, there are a lot of South Florida companies waiting for you to walk in their doors.