The earnings of an ATC will vary because of the traffic level at the facility they are at. A person working in a small tower such as say, Ann Arbor, MI, will not be making the same as a person working in the C90 Tracon in Chicago.
I'm an ATC student so I've spent time looking at the different facility rankings and pay.
I believe facilities are given rankings with 5 being the lowest and 12 being the highest. For example I believe Ann Arbor is a 5 and the C90 is a 12. Most centers and busy tracons are 11 or 12. You can make a pretty nice living at the high end facilities. I know a friend of a friend in the New York Tracon (N90 i think) who claims to be making 170,000 dollars at the age of 24. But that is misleading. I've been told he works a grueling 6 day week with wacky hours. And not all of that 170k is his salary, because he is in NY, he recieves a high "Cost of Living Expenses" or "Locality Expenses."
Right now, it appears the FAA is going to start controller hiring within the next few months after a two year or so hiatus for lack of funds. The rumor I've heard that they will try to hire approximatly 1500 a year for the next 5 years, to replace the controllers slated to retire soon, but that is only speculation.
Here is a old thread which has links to facility rankings and pay.
ATC facilty pay rates
If anybody more knowledgable can correct my statements on facility ratings, etc, please do, I'd really appreciate it for my own knowledge.