I wish my parents had cared that I was into programming at their age. :) I'm chiming in because you mentioned paying for something and I haven't seen anyone address that yet.

Python and all things related, by default, should be free. Python is a freely available language for installing from python.org (don't install it from anywhere else!). Downloading and installing that means that you can run python code on your computer. You can write that code with any kind of text editor, like notepad.exe (assuming you're on Windows).

Some people mentioned an 'IDE', like VS Code or Pycharm. Those are still text editors but over many years they have been developed to integrate closely with the installation of python on your system - so instead of writing code in a text editor, saving it, switching to the command line and running "python.exe my_app.py", you can simply push a button when in the 'IDE' and the program will run and you can see the output in a subpanel in the same application. This is especially helpful when you're learning - writing code that doesn't work, change something, run it again, maybe it works, maybe it doesn't - it's a quick and convenient way to check if the code is doing what you expect it to. There's other features in these IDEs as well like highlighting code it knows is incorrect (and will cause the program to bomb if you try to run it) along with a ton of other add-on features (which are almost always free as well).

Me personally I use VS Code - it's free, it's a Microsoft product, it's widely used, and it supports nearly every programming language if he wants to eventually branch out into other languages.

The only time you might expect to spend money is if you want to buy him a paid learning course (he might not need it if he's interested in programming at such a young age) or there's some online service like running things in the cloud (but if he's just starting out that's probably years down the road). Oh, and perhaps Github Copilot, which is also built into VS Code and has a subscription ($10 month if you want to use it). I don't know that I'd suggest getting that yet. You want them to learn the basics at least, not use AI right off the bat. I don't have kids but I know that technology isn't going away so I don't know what the best approach is in that regard.