As a major input of capital investment in mechanised agricultural operations, farm machinery cost is important to be evaluated before making decisions for its further adoption. This study aimed to evaluate the total costs of an autopilot tractor-mounted real-time plant Nitrogen (N) sensor and autopilot tractormounted real-time soil electrical conductivity (EC) sensor for plant and soil monitoring operation in oil palm cultivation. The estimated total cost for operating an autopilot tractor-mounted real-time plant N sensor was RM5.51 ha-1 or 45.00% lower than that of the current practice in immature palm fertilising operations. Whilst, the estimated total cost for operating an autopilot tractor-mounted real-time soil EC sensor was RM6.90 ha^-1 or 31.14% cheaper than that of the current practice. Considering the average oil palm estate area of 960 ha in Malaysia and the frequency of operation per year, the break-even areas (BEA) for economic justification of owning an autopilot tractor-mounted real-time plant N sensor was five estates, and an autopilot tractor-mounted real-time soil EC sensor was two estates. Despite securing higher total cost saving offered by each machine system was a challenge, however, the machine’s capability of optimising site-specific crop management (SSCM) for managing efficient inputs is a key benefit of this technology.