How much does it cost to build an AI agent for a small business?

No independent survey of UK AI build prices exists. These figures come from agencies that sell the work, so read them as list prices.

Model usage for a small business agent usually costs a few dollars to a few hundred dollars a month. The bill is runs per month times tokens per run times the model's price per million tokens.

Model prices, November 2026

Standard tier list prices in US dollars, checked on each provider's pricing page on 7 November 2026. Anthropic takes 50% off for batch processing.

Worked example with 2,000 runs a month

Take an agent that handles 2,000 customer conversations a month. Each run makes several model calls and reads tool results, so assume 20,000 input tokens and 2,000 output tokens per run. Those token counts are an assumption, so measure your own runs before you set a budget.

• On Claude Sonnet 5.5, 20,000 input tokens at $2 per million cost $0.04 and 2,000 output tokens at $10 per million cost $0.02. That makes $0.06 a run, or $120 a month for 2,000 runs.
• On Claude Opus 5.5, $0.08 plus $0.04 is $0.12 a run, or $240 a month.
• On gpt-6.1-terra, $0.02 plus $0.01 is $0.03 a run, or $60 a month.
• On Claude Haiku 5.5, $0.002 plus $0.001 is $0.003 a run, or $6 a month.

Prices move fast. Google's gemini-4-argon costs $120 a month for this workload until 30 November 2026, then $240 when its rates double on 1 December.

Hosting, monitoring and care

In this example the care fee costs more than the model. Softomate's 2026 chatbot guide puts hosting at £50 to £200 a month for a UK SME build. Its price list starts agent care at £399 a month and bills platform and usage costs on top, even if the client declines care.

Master of Code advises budgeting 15% to 20% of the build cost each year for maintenance. On a £6,500 build that is £975 to £1,300 a year. That budget pays someone to read failed runs, update prompts when your process changes and re-test after a model update.

Gartner predicted in June 2025 that over 40% of agentic AI projects will be cancelled by the end of 2027, because of rising costs, unclear business value or weak risk controls. It also estimated that only about 130 of the thousands of vendors selling agentic AI offer real agents, and called the rebranding of chatbots and assistants agent washing.

Five habits keep a small business project out of that 40%:

1. Write the payback maths before anyone builds. List what the agent replaces, what that costs a year, and the build and running costs.
2. Check that you need an agent at all. A practitioner on r/AI_Agents wrote that 90% of the agent projects he is hired for don't need agents, and a commenter added that a $3,000 automation saving 20 hours of manual work beats a $50,000 agent that solves nothing. See AI agent or automation.
3. Start with one workflow and one measure, such as hours saved a week or tickets closed without a person.
4. Keep a person on approvals for anything that moves money, emails a customer or deletes data.
5. Test on your own data and agree the pass mark before go-live.

Yarigai is a done-for-you AI agency in London that builds AI agents inside a client's own accounts and tools. A project runs in four steps.

1. A free 30-minute scope call on Google Meet. The client keeps the notes whether they hire Yarigai or not.
2. A blueprint, which takes about a week and is credited to the build. It sets out a written plan, a clickable prototype, the monthly running cost, a fixed price and the payback maths.
3. The build, which takes 2 to 6 weeks in the client's accounts, with a demo of working software every week. A single workflow can go live in about two weeks.
4. Optional monthly care, which the client can cancel any month and keep everything.

The client owns the code, the data and the accounts from day one. AI and hosting bills go to the client at cost, and the monthly running cost is on the quote. A person approves anything that sends money, emails a customer or deletes data. Yarigai quotes a fixed price after the one-week blueprint, and its guarantee reads "If the build isn't profitable for you, we won't build it." If the blueprint maths doesn't come out ahead within the first year, Yarigai doesn't take the job. More on AI agents.