I've been reading Michael Lewis's latest book Boomerang: Travels in the New Third World. In it Lewis researches the cultural background of the recent financial meltdowns that we've been happening all over western civilization. Like Iceland, Ireland, Greece, and United States. There's a common thread in every one of them: we all want to do just look at things in the short run, despite the fact the math doesn't work in the long run. We tend to not even do the math until everything goes to hell. Then we are surprised.
I see this same thing happening with beginning real estate photographers. The facts are that:
The biggest struggle for beginning real estate photographers is resisting the pressure from agents that say, "oh I can't afford that much". The fact is agents fully understand and recognize when you are charging too little to be covering your expenses. Listing agents work with other contractors all the time and fully understand what contractors charge in their area to come to a home and spend 2 hours there. But are they going to say, "... I think you should be charging more". No, most will not. You must be hard ass with agents and look out for yourself. Take the time to understand what other contractors (furnace maintenance, window washing, house cleaning, fix-up, etc) charge and how the work you do relates to what other contractors charge.
Decide exactly what's covered in your shoot price and write it down. When an agent hires you the first time have them read and initial your terms of service statement. This is exactly what they do with their clients.
Frankly, there are a lot of lower-end struggling agents that you don't want to work with. Don't be afraid to move on when you need to.