Docker container cost optimization can be approached from multiple aspects: 1) use lightweight base images (alpine, distroless) to reduce image size; 2) multi-stage builds to keep only necessary files; 3) set reasonable resource limits to avoid resource waste; 4) use auto-scaling to adjust container count based on load; 5) regularly clean unused images and containers (docker system prune); 6) use spot instances or reserved instances to reduce cloud costs; 7) optimize application code to reduce resource consumption; 8) use shared data volumes to avoid duplicate storage; 9) monitor resource usage and optimize in time; 10) choose appropriate instance types and specifications.