I put parts I'm likely to replace into Amazon and it's price checkers, and these spark plug were under $2 for quite a while, with a $2 rebate (not sure if they reduce the rebate check based on that)
I got them for $1.88 yesterday, and they went back up in price, but will likely come back down
It is likely the other model plugs may have similar. The NGKs never get that cheap.
They should be the oem denso plugs in an ac delco box
http://www.amazon.com/gp/product/B001KS8LSO