AI Costs Go Pay-Per-Use: Fable 5, GPT-5.5 Pro, and Gemini 3.5 Flash Redefine Pricing

AI pricing is diverging as major models shift to usage-based costs: Anthropic's Fable 5 moves to pay-as-you-go on June 23 at $10 per million input tokens and $50 per million output tokens (subscription allowances may be reinstated later), OpenAI's GPT-5.5 Pro costs $5 per million input tokens and $30 per million output tokens via API, and Gemini 3.5 Flash offers $1.50 per million input tokens and $9 per million output tokens (with a free tier). Costs depend on task complexity, with long-running, multi-step tasks driving higher bills, so users should compare plans and read fine print before choosing.