Soil salinity remains one of the most pervasive constraints to sustainable rice production in coastal and irrigated lowlands. This study develops an integrated agromeliorative cost model using a systems economics framework to quantify the financial viability of reclamation and management strategies in salt-affected paddy systems. Drawing on empirical evidence from Kerala (India), the Mekong Delta (Vietnam), Uzbekistan, and comparative arid-zone cases, the model incorporates dynamic feedback between soil chemistry, water management, amendment application, and crop performance. Simulation results demonstrate that combined use of gypsum (applied at 25–50% of gypsum requirement), farmyard manure, and improved drainage can reduce long-term production costs by 22–38% and increase paddy yields by 26–34% within 3–5 years. Benefit–cost ratios range from 1.67 to 2.41 across scenarios, with net present values remaining positive even under ±25% fluctuations in input prices. The proposed framework offers a replicable decision-support tool for policymakers and extension services aiming to enhance resilience of rice-based livelihoods in salinity-prone regions.