Okay, my bad, I was looking at this page [1] which says that the "Cost Management" feature is available for Pay-as-you-go subscriptions, but [2] is pretty clear on the fact that Spending Limits aren't available for Pay-as-you-go subscriptions.
So, TL;DR: Azure still doesn't allow you to set spending limits on Pay-as-you-go subscriptions
This convinced me that it's maybe worth trying. Given the number of tools out there and how easy git feels for me right now (pretty easy), that's a highish bar
It's also affected by the fundamental barriers to entry in offering a competing product - homes don't get built quickly and people can't move that easily.