Even though I am in Texas and they are in LA, I use a company called Aberdeen Captioning. Their service is fantastic. I make a small format QT movie of my 60 min broadcast, send it to their FTP site and within about 48 hrs. they e-mail me back a QT movie with the capion information over black which I edit into the program.
They have bent over backwards to help me, and I believe this workflow keeps the quality level high (No generation loss on the caption copy). Their rates are real good also.
Aberdeen Captioning
(800) 688-6621 ask for Matt
abercap.com
Don Walker
John 3:16