How much does it cost to build an AI agent?
An AI agent that performs work inside your systems costs $25,000 to $70,000 to build and takes 8-16 weeks. An assistant that only answers questions costs less.
The price splits on one question: may the model act, or only answer. An assistant that answers from your documents is a retrieval problem. An agent that files a refund, updates a record or sends a message is an integration problem with consequences, and everything expensive follows from the word "consequences".
Answering only: $8,000 to $25,000, 4-8 weeks.
Acting inside your systems: $25,000 to $70,000, 8-16 weeks.
The gap pays for the parts nobody demos: human review on every action that costs money, an audit trail of what the agent did and why, a rollback path, a kill switch, and an evaluation set so quality is measured rather than felt.
Running it afterwards costs $1,500 to $6,000 per month for models, infrastructure, monitoring and monthly tuning.
Updated: August 15, 2026