In at least one case a purchase was missed through sheer incompetence. Having been warned about the deadline, India dawdled & delayed until it was too late, then submitted a request for more. IIRC that's not the case where India has tried to buy, or asked for a quote for, something which is no longer available, because the bureaucrats took too long to process a request from the armed forces. The really odd thing is that they submit the requests anyway. It seems that once the process has begun it's unstoppable. And as in the case of the C-17, there's a marked reluctance to scale down the request if it can be partially fulfilled.
When our military procurement cock-ups make me depressed, I think of India, to remind me that it could be worse.