Arduinos + PIR sensors + magnetic sensors + infrared tripwire modules + 433Mhz transceivers + a computer (raspberry pi) with Internet
Another alternative (to non-existing BLE sensors) is hooking up a cheap USB software defined radio stick (like RTL2832) to an Android phone using a USB OTG cable supporting simultaneous charging. That's my current plan anyway.
Arduinos + PIR sensors + magnetic sensors + infrared tripwire modules + 433Mhz transceivers + a computer (raspberry pi) with Internet