Quantum Key Distribution (QKD) is emerging as a crucial technology for securing cryptographic key exchanges against the future threats posed by quantum computers. This study undertakes a comprehensive comparative analysis of four prominent QKD schemes: BB84, E91, B92, and SAG04. The eval- uation is centered on quantum cost and raw key efficiency, key metrics for determining the practical viability of these schemes. Simulations were performed under ideal, noiseless conditions to ascertain the raw key efficiencies, resulting in 50% for BB84, 77% for both E91 and B92, and 49% for SAG04 on average. To further assess these implementations, an established quantum cost metric was employed, yielding costs of 6 for BB84, 11 for E91, and 4 for B92. The IBM Quantum Experience platform was utilized to perform all implementations, providing a robust environment for testing and verification. This analysis aims to provide insights into the trade-offs between cost and efficiency in QKD protocols, aiding in the selection of the most appropriate scheme for different security requirements and applications.