The bonzai looks to be a rebranded HSP touring car. Can be found under other brands like redcat, exceed, himoto, etc. They made monster trucks, touring cars, drift cars, buggies, etc off the same platform.
Parts are everywhere if you know where to look and have been out for a long time. Pretty durable as well depending on what flavor of the platform you pick up and how much power you plan on pushing through it. A brushed drift car shouldn't have too many problems, if any. Monster truck versions of it have issues with the doggones snapping when you jump it, buggy version tends to bend shock towers, shocks leak on all of them, etc. They're built super cheap, but that cheapness ends up being the reason it's so durable. Very little, if any fibre reinforcing in the plastic means its spongey feeling while driving and handles poorly, but the plastics will bend like bubble gum instead of snapping. Aluminum that's used is soft, but you can bend it back 20 times before it finally snaps. Perfect for a young kid or a beginner on a budget, which is exactly why this chassis exists in the first place.
I think your son will have a blast with it and it should be relatively low maintenance for you.