Answer is "yes" we have the resources in public and private
sector to design and build. Some of the electronics may have to be
purchased off the shelf. But the problem is economics....
As a rule of thumb, you need to sell about 400 aircraft of the same
variant in order to just re-coup your R&D and production costs
for these 400. And each aircraft is going to cost you at least USD
70m , excluding munitions. This would buy you an aircraft of about
F16 D or F18 E standard.
The RSAF is unlikely to put in an order for 400 a/c at one shot.
And we are pretty sensitive about exporting our own technology to
other countries. Unlikely to sell more than 150.
So at the end of the day, Mindef might as well do a deal with the
US government and manufacturers , and negotiate to buy more F16 C
or Ds at USD 50+m each.