[cloudexpat]

This is a great example of how unpredictable AWS billing can derail projects. I've seen this exact scenario play out at multiple companies - sudden 700%+ cost spikes that force engineering teams to become billing experts instead of building product.

A few learnings from teams I've worked with who faced similar issues:

1. RDS cost surprises often come from I/O charges that aren't obvious upfront. Moving to reserved instances helps, but doesn't solve sudden usage spikes.

2. The "build your own monitoring" approach works but has hidden costs - engineer time, maintenance, alert fatigue, etc.

3. Many teams find that automated cloud optimization platforms (like CloudExpat, Spot.io, or CAST AI) can reduce costs 60-90% without the engineering overhead.

For anyone spending $10k+/month on AWS/Azure/GCP, it's usually worth getting a free cost analysis. Even if you don't use a platform, they'll often reveal billing patterns you didn't know existed.

Your Beacon project looks solid for self-hosters though - great work turning a painful experience into something useful!