Correct, when you consider economies of scale; cost per unit will drop significantly; i am expecting around 150-250 to be built before a Blk IV comes online. Once learnings are made from Blk 3, it will mature into a Blk IV like II did from I. More from weapons integration and additional capabilities which could involve a newer engine - more guess on this dont quote me on it.I do not think Block 3 will cost that much more than Block 2.
It will anyway be much cheaper than an equivalent F-16.