First of all, you're not doing this for the money. Annual salary? $100k. Christmas bonus? $5k. Taking out Osama Bin Laden? Priceless.
The reality is that, as this is a government job, your income is based on a pay grid. There are 11 government pay grids, with Obama at the top, and obviously it goes down from there. Prove your worth, get promoted, and move up to a higher grid and you'll be bringing home more bacon. It isn't all about your job performance, either. Let's just say it helps to be a bit of a sycophant.
There are also plenty of opportunities to make a ton more on the side, although much of it ain't legal. You might capture a drug dealer with a warehouse full of coke, the proceeds of which have been funding Al Qaeda. Mr. Dealer might offer you a million bucks to go away. Certainly tempting, but not smart, legal, or very patriotic. You'd do best to avoid temptations like this unless you want to be put on trial as a traitor to your country. As you might imagine, a conviction for treason means more than eight days in a county jail.
Many CIA officer salaries are in the $50k-85k range, but because your work as a field officer is a little riskier and more specialized, you can expect to make a bit more than that—think $100-125k. Like everything in government work (and unions), seniority matters. Worked there 10 years? Great. Pay bump. Get a promotion? Great. Get a pay bump. The key idea here though is that if you were the actual guy who shot Bin Laden in the chest, you don't get an $11,000 bonus. It's not like the New Orleans Saints' bounty system.