You can find extremely nice places for around 500-700 Euros per Month depending on where you want to live. Demand for flats is extremely high so it's really a matter of luck. Another 700 Euros to live very comfortably in Berlin (Lunch, occasional dinner, going out on weekends). Standards of living are extremely high in Berlin. I can only recommend this city!
I would say one of them could be in making the utility (electricity, gas, water) more user friendly. Transparency hardly exists and there are seldom interactions between companies and subscribers. Focusing on user experience in this area could be an opportunity...