So, my son’s DS broke

We originally purchased it used on Ebay for Christmas last year. The parts got wet. He had it in a bag for a field trip for daycare and the water bottle leaked. So, it is not like he was irresponsible, but it is broken. We have attempted a few thngs ourselves, but nothing has worked so we contacted the company. We can get it fixed for 85 dollars.

We’d like to use this as a teaching lesson for my son. He is 7. We want to show him the process of saving up for the repair. We’ll talk to him about cutting out some things like sweats etc. from the grocery bill and have him pitch in 20 dollars of his birthday money. But, I’d really like him to understand the process and the importance of not paying for something unless you cut out costs elsewhere.

Anyone have any child friendly ideas for getting this across. My son does have ADHD and so his understand of some common sense things (like time) is behind a typical child. So, maybe think of a 5 year old.

I’m thinking of a chart and maybe an envelope and having him count and chart it, but I can’t quite visualize the best kind of chart to use.