At 14 mil a pop AMP is double what Boeing said it would cost (7 Mil) Most H-Model modernizations cost anywhere from 3-8 million based on the complexity. The US (and other gov) are not dumb, they know what other cockpits cost and that 14 mil is kind of a rip off. (Which is why you don't see alot of people lining up to get this mod)
Nat. Guard programs especially do not like the risk/cost of going to AMP.
On top of all that, the J-Model is not fully CNS-ATM compliant, late, and completely owned by Lockheed. (So upgrades come in blocks and 100 mil price tags) Right now the users of the H-models are kind of stuck between a rock and a hard place as "other" options would involve deviating from the congress spending on AMP and J.
Oh what fun politics are :-D