Why go for 4.5G jets when JF-17 BLK-3 is just round the corner? I think we should go for 2-3 squadrons of SU57 / PAK-FA, as we may soon have to deal with F-35s in our airspace. If we must go for a new 4.5G platforn, I would prefer SU-35 over anything else.
We must also invest in a Missile Defence System HIGHER than S400, maybe the S500.
In $9b, I would also like to add a couple of nuclear subs to the shopping list; times are changing fast, and we need to have one sub closer to the US waters at all times to provide us with an effective deterrent.
With madmen like Modi, Netanyahu and Trump around, we have never come closer to WW3 than we are today. A new grand alliance between Russia, China, Pakistan and Turkey, along with Iran, Syria, Afghanistan, and possibly, even Saudi Arabia, should prove to be a game changer.
India sandwiched between Pakistan and China, and Israel within reach of Pakistan, Turkey and Iran should keep the 'Big Bad Wolf' mostly where it ought to be, closer to the Atlantic, and give the world a new lease on life!