OpenAI added GPT-6 Sol and GPT-6 Luna, mid- and lower-tier API models below flagship GPT-6 Astra that beat their GPT-5.6 predecessors on benchmarks. Luna costs $0.10/$0.50 and Sol $2/$10 per million input/output tokens; OpenAI says the cuts are permanent. Versus GPT-5.6, Sol is 50% cheaper ($4/$20)