I'm new to the MP forum but far from new to UAS (originally called R/C aircraft) and the business of UAS Photography. I would not start a new business based solely on Real Estate Photography. That's a very competitive business and if you're not able to set yourself above your competition you'll be in a bidding war and the only person that wins is your client.
Our base rate starts at $250/shoot plus we have 1/2 and full day rates and we do fairly well. I was very early in the market and built a strong customer base before most people had heard of a "Drone" let alone thought about getting aerial pictures from them.
@Donnie Frank once again excellent write-up my man.