Will the ADVC-110 converter work for this application? Take a "LIVE" analog signal out of a video mixer, convert to firewire for live computer capture of event footage. I also just noticed the ADVC110 specifies only SECAM video input is accepted (720x576@25fps) - however I find positive reviews from US users which are presumably on NTSC. My live capture cameras will be NTSC@29.97fps.

And anyone know of other solutions in $200-300 price range?

Yes, it will work.

The unit can accept PAL, NTSC and SECAM for analog input.
It can generate PAL and NTSC analog output. SECAM analog output is not available.