I think so many people find SLP expensive only because they are coated. Many people don't take that into consideration.
Now I'm not calling anyone out here, but if I were MT and you were posting in my forums, I'd think it would be a slap in the face if you asked where you could get them. Looks like no one thought to post up that you can get them here at mustangtuning.com! For those that don't know how to look them up.....
SOHC
http://mustangtuning.com/slpheaders.html
DOHC
http://mustangtuning.com/slp46dolotuh.html