You could use one of these

You could use one of these:

http://pro.sony.com/bbsccms/assets/files/mkt/broadcast/brochures/anycastHD.pdf

Another forum member has one for sale for only $6,000.00

Have you considered using a rear projection screen and recording it that way?  An inexpensive projector and screen would probably run less than $500.00.

You may want to check out this site and contact the other to see if the “video” can be a live feed into the PC.  http://www.greenscreenwizard.com/GreenScreenZipper.aspx