Hi,
Thank you for sharing this interesting project. We can achieve this by using the triplet circuit board.
To explain simply, the base circuit can have set of threshold detectors and which can raise interrupt signals to the main circuit (built on tope of microprocessor).
Thats can communicate to the PC either via Rs-232 port or wireless module if thats required (may be bluetooth/RF).
In PC we can write a listener (incase of wireless we need to write additional driver). The software listener can be written using simple VisualBasic or a using python script, which can trigger the email notification.
The cost involved in this process are the components (electronic circuit, ICs, processor, wireless sender & receiver, connectors), programming the circuit to monitor the signals/interrupts, software that listens on a PC, and finally the program that sends email.
Hope I gave a short description of what I'm going to do. My brother works for Danieli Automation who will be assisting me with this project.
Please let me know.