Help - setting up a complex wireless network for VOIP or Voice Chat fo

Ok, here is the problem/idea.

We are running live shows with live music (loud) in high school gyms every weekend. We don't have a huge budget for wireless headset products with noise canceling. And we have about 15 people in need of these headsets. We borrowed a system that was "ok" but cost $1000 per headset! Our total budget for a communication system is around $2000-ish...

The thought was this: set up a private wireless network in the gym (actually, we already have this, since our lighting guy uses a tablet to connect to his desktop PC with the lighting suite software and walks around remotely to adjust the light controls).

My idea was, couldn't we setup some sort of VOIP or Voice Chat system using this wireless network? I don't know all of these technologies super well, but my guess is, there has to be something that could work with this and put everyone in communication, and then the only expesne would be buying good noise cancelling mics/headsets that could somehow connect to the VOIP network or voice chat or something?

Also, my guess it might neccesitate having EVERYONE be in the same giant conference call, but it would be nice to control who can hear who. For example:

- Director could talk 2 ways with everyone
- Lightining could talk 2 ways with director and Spot Lights, but no one else would hear him
- Video could talk to camera operators and directors, but no one else could hear me (ie lighting couldn't hear him)
- Director could run from a laptop and while he could hear everyone at any time, he could click to select who he wants to talk to (everyone, multiple people, or one person)

Now that's an ideal world and I realize it might be limited to everyone just being in a big conference call, which would still work, but if there would be a more complicated way to set it up like such it would be amazing.

Also, if there is another solution in this price range that would work better, please let me know. The VOIP/network idea was just an idea that I thought might save a lot of money.

Advice/thoughts?

thanks so much!