Searching room in Athens near centre

Hi I will be around 18 of March in Athens and I am looking at the moment for a nice appartement or studio for me and a friend that will participate with me in the project. If someone can help me, I would appreciate it. the price can be between 150-350 euro for 2 people. The place should be near the city center and reachable with a bus or by walking for 15-20 minutes. that would be the best. Also the place should be near a university, so I can work on the project at the university. The shopping malls should be close, especially supermarkets for groceries etc. If you have any idea, please contact me via my phone number and I will get in touch with you.