Yeah, I posted a link in the Lance King thread last week that sorted all of the $4.99 albums on Amazon. From what I have read, this will probably end today. There are a number of Christian albums, and a lot of Christian metal from those you mentioned plus several others I mentioned in the other thread.
I have gotten:
Newsboys - God is Not Dead
Glass Hammer - Cor Cordium
Russell Allen and Jorn Lande - The Showdown (I had the first two in this trilogy, so I had to complete it)
Seventh Day Slumber - The Anthem of Angels
Theocracy - As the World Bleeds