Personally, I've had the opposite experience. You can set billing alerts that will e-mail you when you cross whatever thresholds you set. On the billing page,

Personally, I've had the opposite experience. You can set billing alerts that will e-mail you when you cross whatever thresholds you set. On the billing page, it has a line item for each thing that costs money. It's not particularly difficult to stop anything, especially when you're just doing hobby projects anyway. If you're OK with insignificant (less than $10) charges on your credit card, it's really not that hard to get pretty far with serverless. Almost everything serverless has perpetual free tiers and the ones that don't (API Gateway, CloudFront, Route 53) have very low usage-based costs (less than $1/mo idle). If you put any value at all on your time, you'd cross these amounts almost immediately trying to setup / learn anything else.