When assessing the price of a diesel locomotive, you must prioritize the Engine Power (Horsepower/kW) and Tractive Effort, as these directly correlate with hauling capacity. Ensure the engine meets Tier 3 or Tier 4 emission standards for environmental compliance. Additionally, verify the Track Gauge compatibility (Standard, Narrow, or Broad) and the Axle Load limits to ensure the locomotive is suitable for your specific rail infrastructure. High-quality AC Traction Motors often command a higher upfront price but offer significantly lower maintenance costs compared to DC alternatives.