Cheap car 500-800 Euro with Tüv Wanted

Hello municipality, as it is already written in the headline, my sister is looking for 39 years (3 children 19/17/7) a small car for purchases and short school paths etc. She comes from Berlin and has addressed me the week whether I can look for her a car. She has demands as well as none, since the budget is also very low. Should Tüv and reliability be enough to claim. She lives in Berlin, Km. approx. 6000 – 7000 km She knows zero with cars, I will definitely be Is there hope for a car what you can find without putting dozens of euros in it? We come from 12165 Plz The oldest son gets his driver’s license in 2 weeks, so he will drive with the car from time to time. With shopping, bringing the smallest child to school, it is all very hard, so the decision fell on a car you yourself is in the insurance at 40- 45% about Mar. ken don’t matter color anything except turquoise and such a bright green I hope it’s all so far understandable and I hope I find something decent for my sister … I thank you so much for all those who want to help me here Thank you and still a nice rest week