Robert Farley's insights in http://thediplomat.com/2014/01/why-do-fighter-aircraft-cost-so-much/ of January 11, 2014 are interesting. for Part of his article includes:
"An under-mentioned point in defense procurement debates is that the purchase of advanced fighter aircraft is often less about national defense than national identity. Both civilian and military leaders tend to resent the idea that neighbors and rivals will own and operate more capable, advanced, and expensive aircraft. Moreover, states don’t simply buy advanced fighters “off the shelf,” as advanced aircraft have historically required long term deals for training, maintenance, and spare parts. Buying a fighter means buying a political relationship."
This partly explains why Indonesia has been buying numbers of Su-27 and Su-30 Flankers, too small to be operationally efficient. Rather than efficiency, national prestige, Indonesian Air Force prestige and monetary commissions for some, may be influential factors.