Perhaps low cost combat aircraft are possible in countries which are too poor and desperate to waste money on anything else.?
e.g. I understand (could be wrong) that helmet mounted sights were first tried out by the South African Airforce - trying desperately to find a way to make their Mirages match up to MiG-23s. They also came up with the Cheetah although perhaps the Israelis are really more responsible for that? Maybe it is just a Kfir with an SA badge - I don't know.
On the ground the Rhodesians pretty well invented mine resistant vehicles starting with the "pookie" which was built from an elongated VW beetle chassis with formula-3 racing tyres. Not exactly high cost - because there was no way it could possibly be high cost or they would never have been able to have it.
I am sure that the SAAF and the Rhodesians would have preferred to have lots of money and no sanctions so they could go out and buy high quality products off the shelf of course.