Baby monitor vs security system

In the market for a baby monitor for obvious reasons but thought there might be a suitable security system with the outdoor security cameras but also an indoor camera with a microphone and option to leave it on over night?

My research has led me to believe I'd get much better quality video, but maybe not as easy interface.

Has anyone had this predicament before and found something effective? Baby monitor about $200 but I'd stretch to 500 for a good security system if it were to work as I imagine.