This one really depends. If you're broadcasting out of a small market for a local studio, you may only make around $50k a year. If you're a top broadcaster on ESPN, then you could be raking in a couple hundred grand. Or, if you're that one in a million type guy like John Madden, Jim Nantz, or Bob Costas, you could be making some serious bank. Like 3 to 7 mil a year. Doesn't hurt if you can get a hugely successful line of video games named after you. (We are, of course, referring to Bob Costas Football: Full Contact Deathblow.)
Obviously, you can make more if you work double-duty. Doing the sportscasting for Monday Night Football will make you a ton of money, but if you can also snag the Olympics gig over the summer, you're going to rake in even more. And you'll do better broadcasting from a booth rather than being an on-field reporter, but that won't be your call. You've got to earn the comfy seat in the warm booth. Which, if you're a Chicago sportscaster, might even be as big a concern as your paycheck.