Cost-LLM: Efficient Multimodal Procurement-Cost Reasoning for E-Commerce Price Governance

Zhiyin Li, Fei Huang, Tengteng Kong, Tang Jie, Shengjie Li


Abstract
Estimation of product procurement cost is a key capability for price governance on large-scale e-commerce platforms: from images, structured attributes, comparable products, and pricing knowledge, a practical system must infer a reasonable cost to surface suspiciously inflated or potentially non-compliant listings. Directly invoking general-purpose VLMs is prohibitive at high QPS (queries per second), and their verbose rationales complicate auditing and rule integration. We present Cost-LLM, a compact 7B multimodal cost-estimation model trained by a two-stage post-training pipeline: segment-normalized SFT on progressive pricing rationales, followed by GRPO with an asymmetric MAPE-based reward aligned with cost accuracy. On an in-house benchmark covering 105 fine-grained categories, Cost-LLM reaches MAPE 29.47% and Acc@20 40.42%, yielding the best point estimates among the evaluated systems. Deployed as an auxiliary signal in a price-anomaly pipeline, it provides a 30.73% relative complementary-detection yield over the production baseline at an audited precision-matched operating point. Its locally deployed serving latency is 0.4-0.8 s per listing, compared with 3-8 s observed for external commercial LLM/VLM APIs. We share the design choices, training recipe, and deployment lessons.
Anthology ID:
2026.emnlp-industry.13
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing: Industry Track
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Pepa Atanasova, Gholamreza Haffari, Minghan Wang
Venue:
EMNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
199–210
Language:
URL:
https://aclanthology.org/2026.emnlp-industry.13/
DOI:
Bibkey:
Cite (ACL):
Zhiyin Li, Fei Huang, Tengteng Kong, Tang Jie, and Shengjie Li. 2026. Cost-LLM: Efficient Multimodal Procurement-Cost Reasoning for E-Commerce Price Governance. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing: Industry Track, pages 199–210, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Cost-LLM: Efficient Multimodal Procurement-Cost Reasoning for E-Commerce Price Governance (Li et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-industry.13.pdf