New one is about Rs. 98,000 at PakWheels.
https://www.pakwheels.com/accessories-spare-parts/toyota-aqua-hybrid-battery-unit-5379844
Mr. Shan Ali is right. You need to carry out the cost benefit analysis between Aqua 2014 and City 2022 from your own perspective.
I work from home and only go out at weekends. So, hybrid was not feasible for me. It may be more cost effective for you.
Apart from cost saving, you should also consider resale.
It will be easier to sell a City at the best rates even 5-10 years down the lane. But you will have difficulty in selling a 15-20 years old Aqua at a good price.
In fact, no person of sane mind will pay 40 lacs for a 20 year old car.
Maintenance cost should also be considered. Every car over 4 years old requires suspension and engine leak etc. repairs.