For AU bank it is mandatory to open an FD worth Rs.30000 even though if you have a Royal Account. You can also consider Indusind Bank Exclusive Bank account. With this you can get 50% off in lockers which will cost you around 1200. Minimum deposit for both AU bank Royal account and Indusind Bank...
Aa far as i know AU bank is providing the cheapest lockers to its customers having Royale Account. You just need to open a royale account by giving them 1 Lac and you are good to go. Locker will cost you around Rs.850