The cost decline for a given level of performance does tend to slow over time

Even in their tests, there are big drops in 2026 models, and recent ones.

A much more comprehensive and easy test is to follow this benchmark suite (AAi). Its a mix of medium/hard benchmarks, with bias for agentic coding. (sorry for url dump) https://artificialanalysis.ai/?endpoints=openai_gpt-5-2-codex%2Cazure_kimi-k2-thinking%2Camazon-bedrock_qwen3-coder-480b-a35b-instruct%2Camazon-bedrock_qwen3-coder-30b-a3b-instruct%2Ctogetherai_minimax-m2-5_fp4%2Ctogetherai_glm-5_fp4%2Ctogetherai_qwen3-next-80b-a3b-reasoning%2Cgoogle_gemini-3-pro_ai-studio%2Cgoogle_glm-4-7%2Cmoonshot-ai_kimi-k2-thinking_turbo%2Cnovita_glm-5_fp8&models=mimo-v2-5-pro%2Cgpt-6-sol-low%2Cgemini-3-5-flash-minimal%2Cgpt-5-6-luna-low%2Cclaude-fable-5-1-low%2Ckimi-k2-6%2Ckimi-k2-6-non-reasoning%2Cmimo-v2-0206%2Cglm-5-3-flash%2Cgpt-6-luna-xhigh%2Cglm-4.5%2Cgpt-5-5%2Cclaude-opus-5-low%2Cmimo-v2-5-0424%2Cclaude-sonnet-5%2Cmimo-v2-6-pro%2Cclaude-opus-4-5-thinking%2Cminimax-m3%2Cgpt-6-astra%2Cclaude-opus-5-5%2Cqwen3-8-27b-non-reasoning%2Cgpt-6-luna-medium%2Cclaude-fable-5-1%2Cgpt-5-6-luna%2Cmimo-v2-5-pro-non-reasoning%2Cminimax-m2-7%2Ck2-horizon-mova-36b-a4b%2Cclaude-opus-4-6-adaptive%2Cgpt-5-6-luna-medium%2Cgemini-3-1-flash-lite-preview%2Cgpt-5-4-pro%2Cgrok-4-3-medium%2Cnvidia-nemotron-3-super-120b-a12b%2Cgpt-6-luna-non-reasoning%2Cqwen3-8-27b-medium%2Cgpt-5-5-medium%2Cdeepseek-v4-pro-0424-non-reasoning%2Cgpt-6-luna%2Cgemini-3-8-flash-medium%2Cnvidia-nemotron-3-nano-30b-a3b-reasoning%2Cgrok-4-5%2Cgemini-3-flash-reasoning%2Cgpt-6-luna-high%2Cqwen3-8-27b-low%2Cmimo-v2-flash%2Cdeepseek-v4-pro%2Cqwen3-6-35b-a3b%2Cgemini-3-8-flash%2Cclaude-4-5-sonnet-thinking%2Cllama-4-maverick%2Cgrok-4-3%2Cclaude-opus-4-8%2Cmuse-spark-1-3%2Cqwen3-8-flash-next%2Cgpt-6-astra-low%2Ckimi-k2-5%2Cgpt-5-4%2Cqwen3-8-27b%2Cqwen3-8-max%2Cgpt-5-5-high%2Cclaude-sonnet-5-5%2Chy3%2Cclaude-opus-5%2Cgpt-5-4-mini%2Ck2-horizon-375b-a23b%2Cgemini-3-1-pro-preview%2Cgpt-6-luna-low%2Cgpt-6-sol%2Cgrok-4-6%2Cclaude-4-1-opus-thinking%2Cglm-5-3%2Cgpt-6-sol-non-reasoning%2Cclaude-sonnet-5-non-reasoning%2Cgpt-5-6-sol%2Cgpt-5-6-sol-xhigh%2Cdeepseek-v4-1-flash%2Cgemini-3-7-flash-low%2Cclaude-opus-5-5-xhigh%2Cclaude-sonnet-4-6-adaptive%2Cglm-5-2-non-reasoning%2Cclaude-opus-5-5-medium%2Cgpt-oss-120b%2Cclaude-opus-5-5-high%2Cglm-5-2%2Ckimi-k3%2Cgrok-4-3-low%2Cdeepseek-v4-flash%2Cclaude-opus-5-medium%2Cgemini-4-argon&agents=claude-code-fable-5-1-max-with-fallback%2Ckimi-code-cli-kimi-k3%2Cgrok-build-grok-4-7-xhigh%2Cmuse-code-muse-spark-1-3-max%2Cantigravity-sdk-gemini-3-8-flash-high%2Cdevin-fusion-cli-gpt-6-astra-xhigh-swe-2-medium%2Cclaude-code-qwen3-8-max%2Cdevin-fusion-cli-claude-fable-5-1-xhigh-swe-2-medium%2Ccodex-gpt-5-6-sol-max-reasoning-effort-max%2Cclaude-code-opus-5-max%2Ccodex-gpt-6-astra-max-reasoning-effort-max%2Copencode-glm-5-3-reasoning-effort-max%2Cgrok-build-grok-4-6-xhigh%2Ccodex-deepseek-v4-pro-0813-max%2Ccodex-deepseek-v4-flash-0731-max%2Cmuse-code-muse-spark-1-3-xhigh&coding-agents=cost&model-creators=zai%2Cgoogle%2Calibaba%2Copenai%2Canthropic%2Cxai%2Cmeta%2Cmistral%2Cdeepseek%2Cstepfun%2Cthinking-machines%2Ckimi%2Cifm%2Cminimax%2Cxiaomi&releases=claude-opus-5-5%2Cclaude-fable-5-1%2Cgpt-6-astra%2Cgpt-5-6-luna%2Cmuse-spark-1-3%2Cgrok-4-7%2Cmimo-v2-6-pro%2Cglm-5-3%2Cgemini-3-8-flash%2Cdeepseek-v4-1-flash%2Cminimax-m3&capability-models=gemini-3-5-flash-lite%2Cstep-5%2Cinkling%2Cmimo-v2-6-flash%2Cglm-5-3-flash%2Cmimo-v2-6-pro%2Cminimax-m3%2Cgpt-6-astra%2Cclaude-opus-5-5%2Cclaude-fable-5-1%2Cgpt-5-6-luna%2Cmuse-glimmer%2Cgrok-4-7%2Cnvidia-nemotron-3-ultra-550b-a55b%2Cgpt-6-luna%2Cgemini-3-8-flash%2Cmuse-spark-1-3%2Cqwen3-8-27b%2Cqwen3-8-max%2Cclaude-sonnet-5-5%2Cclaude-opus-5%2Ck2-horizon-375b-a23b%2Cgpt-6-sol%2Cglm-5-3%2Cgpt-5-6-sol%2Cdeepseek-v4-1-flash%2Cmistral-medium-3-5%2Ckimi-k3%2Cqwen3-8-flash-next&cost=evaluation-breakdown

Opus 4.8 (may 2026), by far best model at the time, gets equaled by deepseek 4 pro (july 31) and 4.1 flash (sept 10th) at less than 1/100th the cost. MiMo 2.6 pro (sept 21) is even cheaper and beats opus 4.8 scores by a wide margin. sonnet 4.6 max to gpt luna high is also a 99% cost drop in a short time for lower performance level models.