LLM prices

I’ve been trying to find the right balance of AI models to use in Micro.blog. Currently we use a few different flavors of GPT, including OpenAI’s cheaper “flex” version when speed doesn’t matter much, such as in the background work that powers Inkwell’s Reading Recap feature. API pricing is a little all over the map, so I thought I’d capture some of the recent prices here, for OpenAI and Anthropic. I’m including a couple older models too, like the retired GPT-4.5. This is per million tokens, input / output. GPT-5.5: $5.00 / $30 GPT-5.4: $2.50 / $15 GPT-5.4 Mini: $0.75 / $4.50 GPT-5.4 Nano: $0.20 / $1.25 GPT-5: $1.25 / $10 GPT-4.5: $75.00 / $150 Opus 4.7: $5.00 / $25 Opus 4.6: $5.00 / $25 Opus 4: $15.00 / $75 Sonnet 4.6: $3.00 / $15 Haiku 4.5: $1.00 / $5 What can we learn from this? I have no idea. Clearly GPT-4.5 was a gigantic model, and so OpenAI changed course into more efficient models. Opus has generally been more expensive, but now is comparable to GPT-5.5.