This may be relevant for you: OpenTok
If you don't like their default WP plugin, you could always build something yourself with their video API. I don't have any personal experience with the plugin, but I had it saved as something I'd like to try someday.
Take a look at OpenTok. Looks like there's a WordPress Plugin for it, too. I've played with their iPhone SDK a bit but the functionality that they offer is really nice. Requires Flash, of course, but works very well.
http://www.tokbox.com/opentok/
This is a free for basic stuff but you can add more as need. It does video but I do believe it will fallback to just audio.
Also Google Hangouts has an API so that your site can create and launch Hangouts.
EDIT: Both OpenTok and Hangouts can use Flash, Hangouts will try to use HTML5 first
Not to sound rude but, you need a lot more than "a little help" and it seems like you're asking for someone here to completely lay out what you would need to do. That being said, for what you're talking about, at a bare-minimum, you're looking at:
The prices on all of the above can vary pretty widely but, you can find rough prices pretty easily online, as well as bandwidth calculators and other things to give you a start; not to mention that I'm sure lots of sites/businesses would be happy to give you info for a class project.
If you use a service like TokBox you can probably cut down a lot of development and bandwidth costs but, if you don't luck out and find a developer who will also maintain the site, as well as catch some other breaks/make smart decisions, you could also need things like a webmaster, to pay for additional bandwidth and a lot of other variables.
And, like jackthiscracker touched on, there are different ways to do what you're wanting which will yield different results and for different prices. Since WebRTC isn't ready for heavy adoption yet, you'll probably pay a lot more to find someone who knows the technology, than putting something together using Flash.
One last point, since you posted in a web developers' forum: for a developer to actually be able to help you at all, you need to clearly define the scope and requirements of your project. You don't say how many cameras in a session, how many users total, what browsers/operating systems that it needs to work on or really anything specific for someone to help you.
TL:DR; $50,000. "One-time? Yearly? Monthly?" Yes.
Have any of you ever set up mucki or jwchat with openfire? I found a few other apps but I want to KISS as much as possible
This looks amusing but I just don't imagine people want to video chat with each other much on this site. Perhaps I could be wrong, that said I guess we could accomplish a similar goal with a google hangout? http://www.tokbox.com/
I also asked here, since it seems like they would be able to get the info the fastest since they gave them an award: http://www.tokbox.com/blog/techcrunch-disrupt-hackathon-round-3/#disqus_thread
Edit: according to a later post, they both went to Carnegie Mellon.