I know I'm late to this thread but I've got some thoughts that I think are worth sharing. Before I get started let me say this. There are lots of comments in this thread which are stated in a way that suggests they are fact when in reality they are the opinion of the poster and nothing more. My comments in this post are going to be a mixture of both opinion and fact but I will do my best to point out which is which.
All of this first bit is opinion only. I know lots of people will argue with me on this but if you bought a Phantom 3 with the sole intention of using it for commercial photography, you bought the wrong drone. There is indeed a market for drone photography. But by and large, the people who are doing it for profit successfully are using equipment with price tags and capabilities that lie quite a bit North of a Phantom 3. Please note, I'm not saying professional level shots and video can't be done with a Phantom 3. I'm saying if that's the ONLY reason you bought it, you bought the wrong drone. If all you're ever going to do with it is fly it for commercial photography, then you need a platform that can fly when you need it to fly regardless of what the winds are doing or what the light looks like. A Phantom 3 simply isn't that drone. Give it the right conditions and it will fly great and shoot great looking images. But flying for hire means you fly when the client wants not when mother nature does.
Now for the regulations thing. First the most important fact you'll find on this topic. The FAA has yet to make it clear what exactly constitutes commercial use of a drone. We can talk about how they've ruled on the topic of commercial use of aircraft in the past but there is no way to know whether any of those rulings will apply the same way to UAVs once they make up their minds.
There was once a case where a private pilot was given a violation for conducting a commercial flight (for compensation or hire is the way they describe commercial operations) even though no money changed hands. They have ruled that in those cases 'good will' can be considered compensation for the purposes of the regs. Will they hold UAV's to the same standard? No one knows.
The regulations for private pilots also clearly state that a private pilot may fly an aircraft in furtherance of a business so long as the flight is incidental to the business purpose. The example often cited to clarify this is a business professional who is a private pilot and must travel for a business meeting. Because that pilot could simply drive to get to the business meeting, that private pilot could also fly there because in this case, the use of the place is incidental i.e. just flying from point a to point b which any private pilot can legally do for recreation. And again it remains to be seen whether or not the FAA will apply the same logic to UAV's. But its my opinion that if they do, a plausible case could be made that use of the UAV is incidental to the photography operation because I can easily use a tethered balloon or a camera rig suspended from a kite to achieve the aerial shots I want.
And finally this. The FAA rarely goes looking for violations. Most of the time the only reason they investigate anything is if someone or something brought the issue to their attention. Get your business big enough that you're taking work away from someone who actually holds a commercial waiver and you bet they'll file a complaint against you. Or have a mishap which makes the 6 o-clock news and you could get a letter or a phone call. But if no one ever tells the FAA what you're doing, you might be able to operate a profitable business for quite a while.