Orrr AWS could just buffer it for you. Algo.

1) you hit the cap 2) aws sends alert but your stuff still runs at no cost to you for 24h 3) if no response. Aws shuts it down forcefully. 4) aws eats the “cost” because lets face it. It basically cost them 1000th of what they bill you for. 5) you get this buffer 3 times a year. After that. They still do the 24h forced shutdown but you get billed. Everybody wins.