This can be accomplished for that budget. I recommend Dahua 4300 bullets or Hikvision DS-2CD2032-I. I would also use a Dahua NVR. Im sure Hikvision NVR's are great too but I have no experience with them. As far as the two way audio goes I cannot recommend any because audio recording is illegal in my state. I would also recommend recording 24/7. Hard drives are cheap enough and it just makes sense. You do not want to miss any activity. Just my 2cents.