Firewire camera help

So i have an intel based 21' imac that i use for a broadcasting show I currently have a 2 camera setup the built in isight and a webcam, the webcam broke but i did not like the quality anyway plus id like the zoom function which webcams don not have... ive done my research and i believe i need a mini dv camcorder with a firewire output so i can broadcast/ stream live... i know they dont really make firewire camcorders anymore so i was wondering will a normal everyday camera be fine quality wise i know it will already be better than a webcam... or do they make a hd firewire camcorder... if so what are my options or if you know another way i can broadcast please let me know...ps i can found this for 50 bucks Sony DCR-HC28... sorry for the run-on post

 

im looking to do this the least cost effective way possible Thanks for the help

 

im asking a few questions 1 is the camera i listed at the bottom ok for what i need or do they make a better one or a version in hd or if someone knows another way of doing the things i listed thanks ..its live how... how do i go about moving the thread