For Anthropic, 5 minute caching costs 1.25x base input price and 1 hour costs 2x base input price. https://platform.claude.com/docs/en/about-claude/pricing#pro...

For OpenAI, it seems like you can't prolong the caching duration for money. Duration is longer during off-peak hours for in-memory caching and up to 24 hours for extended prompt caching. https://developers.openai.com/api/docs/guides/prompt-caching

For DeepSeek, caching duration of at least 12 hours (and likely longer) have been observed. Cache writes are free. https://zhuanlan.zhihu.com/p/2035737726952194774