firstly the bow sections have been completed, the cost of the carrier conversion has already been built into the project so there is no real cost in the conversion, as to the aircraft the DOD today anounced that the JSF will now intodays Dollars cost 135 million each, note without source codes, the operation costs are also double that of the F18 , eurofighter, the grippen and the rafale are even lower per unit based on current costs.
while yes the JSF is 5gen plane the cost is still rising the USN/Marines have already said they will now be revising there unit requirements based on the defence budgets, the Australian airforce while they have anounced they will only buy intially 14 aircraft, however not a single confirmed order has been placed. norway ,denmark are now looking more and more towards grippen.
as to training deck crews you seem to forget the uk perfected carrier operations and still retain skills from the carriers we have currently, so deck training is not an issue as such, part of the issue the UK has while wanting stovl verson to replace the harrier it also offers the option to cross deck with other naval warships such as ocean , albion, insupport of commando operations.however this verson is to cost more and as such the UK options would be to have the same verson as the RAF though navalised for consistancy in parts and training ect.
the F18 has been reported to have a airframe crack issue though not on the b,c,d versions and in the states they have grounded some 138 todate, and checks are on going on the others, the fighter has to fit into each countries budgets as the intial costs were agreed in 2002 at 2002 prices, before the world financal problems and constant cost overruns.
as a result rafale grippen are looking a better cost effective option while they are 4.5 Gen they are offered with full source codes, JSF may out price its self, mean while the US are now looking at the F18 life extenshion as a result of the continued delays and costs increse. this may well also extend to the RAAF, and other users.
while rafale have no other current users they have already been offered to the UK at a considerable discount with agreed upgrades which would be required by the RN. at the current rate the two carriers will be comissioned some two years before they see the first JSF