Other than factory direct I have seen them in the $323 range shipped for stainless. I recommend titanim, but thats going to cost a couple hundred more.
I found the V6 part 1920S Available for the price I mentioned. Its stainless V6 headers from JBA. The V8 headers same brand are $327 free shipping for stainless.Also, I realize the OP didn't actually say he was looking for SE headers, but those headers linked are not 3.5L headers.
I assume he's looking for 3.5L headers as they are posting the SE forum.
I've been wrong before, however.