Here's a link that includes a post by me that lists what components I used and how much they cost, I'm sure prices have changed:
https://ogrforum.ogaugerr.com/...64#80973530448820964
I recharged batteries yesterday, some of them have been sitting idle since June 2019 and barely required a charge at all. One engine had been run quite a bit but not since August. When I turned it on it ran about 1/2 way around the layout and stopped, knew it was time to put it on the charger. A freshly charged battery in an engine that is stored will IMO keep for 6 months, maybe more. I have yet to have to replace a battery. These things are good for hundreds of recharges. Other than a loose wire (my fault) I have had no issues with components breaking.