Building an Active-Active AWS Architecture for $47 a Month

Built active-active cross-region architecture for $47/month total: DynamoDB Global Tables ($18) + Aurora Serverless read replicas ($23) + S3 replication ($4) + CloudFront ($8). 90-second failover. Zero data loss. 8 months in production. Survived two AWS regional failures. Not truly active-active for writes, but perfect for SaaS under 10K users. Complete architecture, cost breakdown, and the DynamoDB conflict bug that almost killed us.