If they wait just a little bit longer won't there be lots of earlier F-18s going cheap? Think of the money saved. After all if it is a need to put wings on a new carrier and then parade off some snitty Third World country whose inhabitants won't know the difference between an early [very cheap] and late [much more expensive] model F-18. Let's face it with the reduction in hours flown, why buy anything flyable at brand new prices! They will never reach anywhere near their time-expired/weary wings date.
In fact seeing as the Royal Navy has been told not to upset those naughty pirates why not build some Pinewood Studios replica battleships [all phoney but looking authentic] at a fraction of the normal cost and save even more money?
I just do not understand why we shell out billions in aid to third world countries and decimate our own armed forces [ who are essential for our well being].