It varies from bank to bank and also on locker size. It can be 30K-100K+. Upscale banks (or perceived to be so) will charge more for same size locker.
Better option is to go for yearly rental basis. The break-even on upfront amount and value of that money over time plus the yearly depreciation and inflation does not work out in your favor unless you are sure you will keep the locker for 15-25 years at least.