The Real Cost of Building AI Products in 2025
Key Takeaways
- •Model API costs are only 15-25% of total AI product expenses
- •Evaluation and testing infrastructure costs 20-30% and takes 3-4 weeks to build
- •Expect $3,000-8,000/month in ongoing costs for meaningful AI features
- •Prompts are never done and require continuous iteration as a maintenance cost
Beyond API Pricing Pages
When founders ask us "how much will the AI part cost?" they are usually thinking about API pricing per token. That is the smallest part of the picture. The real costs of building AI products include evaluation infrastructure, prompt management, observability, edge cases, and the ongoing cost of keeping AI features reliable.
The Cost Breakdown
Model API Costs: 15-25% of Total
Yes, API costs are real but they are predictable and declining. OpenAI, Google, and Anthropic have cut prices by 50-80% over the past year. A typical B2B SaaS product with 1,000 daily active users making 10 AI requests each costs $500-2,000/month in API calls.
Evaluation and Testing: 20-30% of Total
This is the cost most teams underestimate. You need automated evaluation pipelines, human evaluation for edge cases, regression testing when you change prompts, and A/B testing infrastructure. Building this properly takes 3-4 weeks of engineering time.
Observability and Monitoring: 10-15%
Tools like Langfuse, Helicone, or Braintrust are essential for production AI. You need to track latency, token usage, error rates, and output quality. Budget $200-500/month for tooling plus engineering time to set up dashboards and alerts.
Prompt Engineering and Iteration: 15-20%
Prompts are never done. User feedback, model updates, and new edge cases mean continuous iteration. Budget for ongoing prompt optimization as part of your maintenance costs.
Infrastructure: 10-15%
Vector databases, caching layers, queue systems for async processing, and CDN for serving AI-generated content all add up.
Total Estimate
For a mid-stage startup adding meaningful AI features: expect $3,000-8,000/month in ongoing costs and 2-4 months of engineering time for initial implementation.
Frequently Asked Questions
How much does it cost to build an AI product?
For a mid-stage startup, expect $3,000-8,000/month in ongoing costs and 2-4 months of engineering time for initial implementation. API costs are only 15-25% of the total.
What are the hidden costs of AI products?
Hidden costs include evaluation infrastructure (20-30% of total), observability tooling, prompt iteration, vector databases, caching layers, and queue systems for async processing.
How much do AI API costs typically run?
A typical B2B SaaS with 1,000 daily active users making 10 AI requests each costs $500-2,000/month in API calls. Prices have dropped 50-80% over the past year.