Indigo Domotics

Can someone please assist in determining what brands of Window / Door sensors work best?
What are the cheapest window / door sensors that work?

Rather than stand-alone door window sensors talking to Indigo, you might investigate incorporating an alarm system. Then all of your sensors are essentially doing double duty-- both as alarm triggers as well as available for Indigo to use.

Plus, some of the large alarm companies have been making these things for a long time and the quality can be very good.