A $500 RL fine-tune of a 9B open model beat frontier models on catalog review

Fermisense GRPO-fine-tuned a 9B open-source model for catalog review and hit 87.3% quality vs. 76.9% for the best frontier setup. Cost per 1,000 listings: $0.50 for the fine-tune, $19–$172 for frontier models. The post calls this 'intelligence ownership'—training a specialist on your own data, tools, and scorer beats prompt-tuned frontier APIs on both accuracy and cost. Ramp data is cited: top-quartile AI spenders more than doubled revenue from Nov 2022 to Dec 2025; zero-AI-spend companies grew ~15%.

Why it matters: Hits all three HKR axes with concrete numbers, named method, and cost comparison. Not scored higher because it's a single company blog post with no third-party reproduction or cross-source verification, and Fermisense sells this solution — conflict of interest exists. But the ...