This study aims to investigate state-of-the-art methods for scalable database management, focusing on cost-effectiveness. The study compares two commonly used NoSQL databases, MongoDB, and Cassandra DB, with a traditional relational database management system, PostgreSQL. The comparison is made through performance evaluations conducted on multiple clusters encompassing cloud and on-premises environments. The evaluations include database operations such as insertion, selection, and deletion. The study results indicate that each database management system is optimized for particular use cases. The choice must be based on a comprehensive assessment of multiple factors, not limited to scalability and performance. The novelty of this study lies in its scalability comparison of three popular database management systems and its emphasis on cost-effectiveness while evaluating performance in different environments.