Hi! Would you like to be notified via email when someone enters your flat or room ? To get an image of that individual? Just push a button when you leave and apply a RFID badge when you get back. It is cheaper and easier to build than many think - it cost me about 50$ and took me a few hours to build and write the code. And it was fun! See description in a PDF file. You might skip the "zoneminder" part at the beginning, and maybe get back to it when your needs grow.