Hi,
I have been working with Cisco VoIP since 2001 and Asterisk and freepbx ,trixbox, elastix since 2007.
I really love the idea you have and would really love to implement that as well,
I would have given that just for fun had this not been my actual/only job :)
we can get really creative with this kind of system ( right now nothing really comes to my mind , but there is room for a lot).
I know my bid is even higher than the max you mentioned , but I actually understand how much work this kind of project will need and the price should have been 500USD not CAD but i'm trying to keep my lowest.
That being said I would like to have a little chat about your project to better understand the needs of the project
regards,