Custom AI integration cost UK: when off-the-shelf is enough

What does a custom AI integration cost?

Off-the-shelf AI tools cost roughly £20–£200 a month and cover most single-person, single-tool jobs. A custom AI integration is a one-off, fixed-scope engineering project: in the 2026 UK market, typically £2,000–£10,000 for AI wired into one system, and £10,000–£30,000+ where it spans several systems or ships as a feature in your product (illustrative market ranges, not our rate card).

For our own pricing: every project starts with a free audit and ends in a fixed-scope quote you approve before any code is written. For complex work, a deeper paid discovery (the Automation Roadmap) is available and credited in full against the build if you go ahead.

When off-the-shelf is genuinely enough

Start with a subscription when the job is one person using AI inside one tool:

• Drafting and rewriting. A ChatGPT or Claude subscription covers emails, proposals and first drafts for a single user.
• Meeting notes and transcription. Purpose-built tools do this well out of the box.
• A FAQ-style chatbot from a template platform. If it only needs to answer from your website content, a monthly tool covers it.

If that describes your job, buy the subscription and stop there. The comparison logic is the same as for workflow tools: DIY Zapier vs hiring an automation agency covers where the ceiling sits.

When custom pays back

A custom build earns its price when the AI has to act inside your systems rather than chat in a separate window:

• Volume with a deadline. Two hundred documents read, extracted and filed by 9am inside the software you already run is an integration, not a subscription.
• The output has a destination. Reading an enquiry, updating the CRM, raising the task and filing the attachment means the AI is wired to those systems with rules and testing.
• Your product needs the feature. AI inside your SaaS, built to your spec, on your accounts.
• Your data needs a defined path. Scoped data flows, documented and kept inside the environment you approve, are part of the engineering.

That is the job custom AI integrations exist for: a fixed scope before any code, the API and model engineering handled for you, tested against your inputs before launch.

What drives the price

• Integration surface. How many systems the AI touches and how well their APIs behave. One document store is straightforward; document store plus CRM plus accounting is architecture.
• Model work. A well-prompted single task sits at the low end. Evaluation against hundreds of your inputs, tone tuning and an escalation path to a person sit higher.
• Data sensitivity. Scoping what the model may see, and where results may flow, adds design and documentation time.
• Support after handover. Documentation and handover are included in a build; ongoing monitoring and improvements are a retainer.

Off-the-shelf vs custom at a glance

Illustrative 2026 UK figures. Build ranges are typical market rates, not a rate card.

FAQ

Do I need technical skills to commission a custom AI integration?

No. You describe the outcome you want; the engineering, the scoping and the model choice are handled for you, with every decision explained.

Which AI models does a custom integration use?

Typically frontier models such as Claude (Anthropic) or OpenAI, chosen per task and budget rather than tied to one vendor. The recommendation and its trade-offs are set out in the scope.

How long does a custom AI integration take?

A single-system, fixed-scope integration typically takes a few weeks. In-product features and multi-system work take longer, with the timeline written into the quote.

When is an off-the-shelf tool the better buy?

When one person uses AI inside one tool at modest volume, and the output needs no onward journey into your systems. Buy the subscription, prove the value, and revisit custom when the copy-and-paste between tools becomes the job.

Get your fixed number

Tell us what the AI should do inside your systems and you'll get a free audit and a fixed-scope quote, including "start with an off-the-shelf tool" when that is the right answer.