The issue here is really Billing... AWS Budgets allows you to set a budget as far down as $1 USD... however because billing is done piecemeal, it is possible to

The issue here is really Billing... AWS Budgets allows you to set a budget as far down as $1 USD... however because billing is done piecemeal, it is possible to have up to 24 hour delay for charges... You can spend $500,000 on AWS in 24 hours, it's not difficult, it's not easy but you totally can blow past your "budget" because it's not a hard cap.