Well so far it is 'exploring options' so no guarantee that it will go forwards, That said assuming future governments don't rip this up and knock out much of what has been put forth (Which really isn't much, it's just one of the few times we have gone and planned ahead and there acquisition is spaced out over a decent time frame) they have costed a decent budget towards it that would allow for the acquisition of around a dozen give or take.
Some things to also take into account, We only have a limited number of CH-47's so any that are based on board any ship are ones being denied to use in land based operations. If using the CH-47 from a ship then you have to get very close to the target, With a combat radius nearly half that of the Osprey depending on the location you could very well be putting the ship in harms way when it didn't need to be the case.
An Osprey acquisition would not only make our air assets more capable but also provide better protection (in range) to our ship's, Quite simply a $100 - $200m aircraft (depending on what is included and how it is costed) is a small price to pay for something that could mean the difference in the safety of a $1.5 billion dollar LHD and the 400+ (Could be up to 1,400 with out overload) personnel on board.
