It is reputed that the tourist who took a snap of Concorde coming down in flames at CDG Paris received $50,000 for one picture.  I am sure the guy with the video camera made a lot more.

Get the content right and your million will soon be in the bank  

Perhaps a peruse through this list could provide some inspiration
http://most-expensive.net/photograph-world

As for me I received a reasonable fee and expenses doing a commercial shoot for a company that wanted publicity photos for their catalogues and web site.  I am not a professional photographer and did it out of interest and a challenge.  To get those jobs regularly enough to pay the bills would be hard work, the photography is the easy bit. 

Best follow Gregory Crewsdon's example he makes 6 prints of each image he does and sells them for around $60,000 a piece. He has a waiting list of prospective buyers I am told . 

And every one said, 'If we only live,
We too will go to sea in a Sieve,---
To the hills of the Chankly Bore!'
Far and few, far and few, Are the lands where the Jumblies live;
Their heads are green, and their hands are blue, And they went to sea in a Sieve.

Edward Lear
http://www.nonsenselit.org/Lear/ns/jumblies.html