Indonesia needs to consolidate on a single platform or at most 2. It currently operates F-16's, SU-27/30, F-5 and Hawk 200's all in combat roles...
For guaranteed supply, I wouldn't discount America. America may withhold supply of parts etc, for political reasons, but IF you remain in their good books, your laughing. Russia from all reports has trouble maintaining supply of spare parts and the serviceability of their aircraft is pretty ordinary from all accounts as well.
I would therefore recommend Indonesia concentrate on a force of F-16's. Numerous second hand variants are available, for quite reasonable prices. They also provide known high levels of capability, plus Indonesia already has the advantage of extensive corporate knowledge of the type, having operated it for 15+ years.
Given the reasonable price of second hand F-16's, Indonesia may be able to afford enough to replace it's whole fleet.
Upgrades which keep it near the top of worldwide fighter capabilities are also widely available and are performed by any number of companies. F-16 is one of the few platforms that Indonesia has been able to maintain in-service, despite US sanctions. It wasn't even able to maintain it's C-130's...
The Su-27/30 purchase has been a serious waste of limited monies IMHO. It smacks of "Generals" with "dreams beyond their means" to me. Even in late 2005, TNI was "hoping" to receive enough funding to be able to even ARM their existing ones...
They are an expensive fighter to buy AND an expensive fighter to maintain and offer little capability advantages over late model F-16 variants, IMHO. The cost appears to outweight the benefits in this instance. They are also a "pig" when it comes to servicing and sortie rates from all reports.
Mig-29 variants might also be another option, but again could Indonesia afford to fund enough aircraft to replace it's existing fleet? If so, great a new fleet of MiG-29's would rejuvenate Indonesia's combat capability and give Australian force planners, something to chew on...