What an AI Agent Actually Costs to Build and Run
Most AI agency quotes hide three big costs. Build, inference, operate — here's the honest breakdown of what you'll pay in year one and what's missing from the quote.
NeuroX AI · April 27, 2026
When founders ask "how much does an AI agent cost", the honest answer is three numbers most quotes hide.
Build (one-time): $15,000–$60,000 for a production single-agent build. The cost driver isn't the LLM — it's the eval suite, guardrails, and integration with your auth system. Quotes that skip evals are quotes that ship vibes.
Inference (recurring): $0.05–$0.30 per agent execution on Claude Sonnet, $0.02–$0.10 on open-source. A sales agent qualifying 200 leads/day = $1,200/month. Most teams build with the most expensive model and never optimize. A 4-day cost pass typically cuts inference 40–70%.
Operate (recurring): $1,000–$3,500/month for a managed retainer. Covers eval review, drift catches, model swap evaluations, and incident response. The line item nobody quotes upfront. OpenAI and Anthropic update production models without telling you — we've seen 8% accuracy drops overnight.
A realistic 12-month TCO for a mid-complexity agent at NeuroX rates: $32,400 total. Median competing quote: $93,000 plus a hidden inference bill.
Three questions that surface gaps in any AI quote: what's in your eval suite at launch? What's projected inference at our volume? What does month 6 look like? Get a written cost projection.