If you want to save money you don't let go the biggest name in cricket. It's why Dhoni could probably play for CSK until he's 50.
That is the only reason why Bangalore have persisted with Kohli. It is no coincidence that he gets to be captain despite comfortably having the worst win percentage as a captain with so many games in IPL history. As for money saved, I meant the impact of having 17 crores invested in one solitary player with a fixed salary cap. For that amount of money you would expect a 2016 Kohli every season and instead you could comfortably get two Indian internationals in your side and still have cash left over to sign an undervalued overseas player.