According my model,

My cost is (I use nous as provider)

DeepSeek v4-flash-0731 • Your cost: $0.56

DeepSeek v4.1-flash • Your cost: $1.22

GPT-6 Luna • Your cost: $4.22

My usage is heavy on the cache. Apparently v4.1 flash uses 1.75 times as many tokens so still cheaper.