Thailand did it a similar way, with it's Gripens. It stated a requirement for 12, could only afford 6, ordered them and several years later placed an order for a follow-on batch of 6 to meet their original requirement. It wouldn' t surprise me to see them order more in this way in future years.
PAF would need to do something simliar, but 6 would at least get them back into the fighter business and the limitations of such a small fleet could be clearly demonstrated...
The RTAF order was a little bit different though. It was for an actual combat system of six Gripens as well as a Saab 340 'Erieye' AEW. Also if memory serves (and I admit it could be failing...
) the initial order allowed for options so that the RTAF could increase the number of Gripens in increments. Another key difference between the PAF and RTAF is that the RTAF already has a number of fighter aircraft stil in service, the Gripens were/are to replace older fighters in service, not re-constitute a capability.
A number of the various orders different Air Forces place for fighters are contracts for
nn of price
yy, with the actual payments broken up and spread out to coincide with completion/delivery of the fighters. Again, if memory serves, there was a recent payment of ~$233 mil. for the delivery of ~6 F-16's to Greece, though it might have been a different country instead.
Really where I question the wisdom of the purchase is that so far there appears to be a commitment to purchase six fighters, yet no announcement for what the desired total numbers of fighters are, their intended roles, what sort of timeframe is expected for the total plan to be realised, and/or the expected total acquisition cost.
I expect most of us are aware that the global economy is still having some issues, with differing regions and countries being more greatly effected than others. With that being true, and the relationship between fighter aircraft cost and the Philippine, AFP, and PAF budgets, it is distinctly possible that another financial crisis could occurr, which could preclude the PAF from acquiring more fighters of the same model as is currently planned. Or even worse, there could end up being an indefinite delay leaving the PAF with just the six fighters ordered.
If the PAF is really looking to get back into fast jet/fighter operations, I would probably look at purchasing a number of the South Korean TA-50 Golden Eagle supersonic advanced trainer/light attack jets. These can perform the advanced jet training which the current PAF jet trainers do, but also fufill some of the roles of a fighter jet. Given their cost of ~$25 mil. per aircraft, they are not as expensive as new-build fighters or even some upgraded/MLU'd fighters. At the same time, if the PAF gets 'stuck' budget-wise, the Golden Eagles can still be used as jet trainers, albeit more capable and expensive than other jet trainers in inventory.
Something else worth considering IMO is having the AFP begin discussions with other countries about the possibilities of joint and/or foreign bases on Philippine soil. For a very long time, the US maintained bases in the Philippines, in part due to the relationship between the countries but also due to the location of the Philippines. While the US-Philippine defence relationship is not what it used to be, the US might find having a base(s) strategically useful again. The Philippines could benefit from potential access to US equipment, and/or interoperability with US forces. Also there would be the economic benefit from US personnel stationed in the Philippines or taking leaves, injecting US currency into the local economy. Another potential candidate for an overseas base would be Singapore. Given the Singaporean (sp?) defence situation, a good portion of the defence forces are stationed overseas due to training and space limitations. As such, it could be beneficial to them to have some forces (RSAF in particular) stationed in the Philippines. Currently some forces are stationed in Australia, but if those forces needed to respond or relocate to Singapore, they would need to overfly Indonesian and Malaysian air space. Having additional forces which would not necessarily have to come in from the same vector could help. On the Philippine side, there could be benefits similar to if the US had a base in the Philippines again as well.
-Cheers