How Much Does a Custom AI Agent Cost in 2026? A Defensible Breakdown

Q: Why is there such a wide bracket?

Because 'custom AI agent' means very different things. A single-purpose extractor plugged into one well-documented API is two weeks of work. A multi-step decision agent that touches your CRM, ERP, and internal knowledge base under human-in-the-loop review is a quarter of work. The five inputs (scope, integration, eval, ops mode, data sensitivity) decide where you land.

Q: Can I just buy an off-the-shelf agent for less?

If the problem is generic, yes. Hire us when the integration with your existing systems, your data, or your compliance posture is the hard part , that is where off-the-shelf falls down.

Q: Why does eval cost so much?

Eval is what separates a demo from a product. A production AI feature without an eval suite is a science project. Eval is usually 20-30% of the total project cost and the line item most agencies skip to hit a demo deadline.

Q: Do you take equity instead of fee?

Fixed-fee or retainer for most engagements. Equity on a small number of early-stage builds when timing is right. We do not lead with equity offers and we will not skip discovery week even for equity work.

How much does a custom AI agent cost in 2026? The honest answer is between €15,000 and €120,000+. That bracket is wide for a reason: a custom AI agent can mean a single-purpose extractor plugged into one API, or a multi-step decision agent integrated with a CRM, ERP, and internal knowledge base under human-in-the-loop review. Below is the cost model we use when scoping at Resser Solutions.

The five inputs that decide the price

01Scope: single-purpose vs multi-step decision agent.
02Integration surface: how many of your systems the agent touches (CRM, ERP, DB, internal APIs).
03Eval requirements: how rigorously we measure quality before deploy.
04Ops mode: cloud LLM vs on-prem / VPC-isolated open-weights.
05Data sensitivity: GDPR, HIPAA, SOC 2, air-gapped environments.

Cost brackets we actually quote

Bracket	Scope	Integration	Eval
€10k - €25k	Single-step agent or LLM feature inside an existing app	1 system, well-documented API	Basic eval set, < 100 cases
€25k - €50k	Multi-step agent with tool use	2-3 systems, structured outputs	Eval in CI, prompt versioning
€50k - €100k	Production agent for a real workflow	3+ systems including legacy / on-prem	Eval, observability, audit log
€100k+	Sovereign deployment or multi-agent orchestration	Inside your VPC or air-gapped	Custom eval harness, regression suite

What the line-items contain

Discovery week (fixed fee, low five figures)

One week. We read your codebase, talk to your engineers, sketch the eval set on actual examples, and write the spec. Output is yours either way. A common output is 'do not build this yet' because the data is not ready or the problem is solvable without an agent.

Prototype sprint (2-3 weeks)

Working slice in your environment. Real integration with at least one of your systems. Eval suite live by week 2.

Hardening (2-6 weeks)

Eval running in CI on every change. Cost cap per request and session. Retry logic, fallback chains, observability for prompts and completions, audit log, runbook for on-call.

FAQ

Frequently asked.

Why is there such a wide bracket?

Because 'custom AI agent' means very different things. A single-purpose extractor plugged into one well-documented API is two weeks of work. A multi-step decision agent that touches your CRM, ERP, and internal knowledge base under human-in-the-loop review is a quarter of work. The five inputs (scope, integration, eval, ops mode, data sensitivity) decide where you land.

Can I just buy an off-the-shelf agent for less?

If the problem is generic, yes. Hire us when the integration with your existing systems, your data, or your compliance posture is the hard part , that is where off-the-shelf falls down.

Why does eval cost so much?

Eval is what separates a demo from a product. A production AI feature without an eval suite is a science project. Eval is usually 20-30% of the total project cost and the line item most agencies skip to hit a demo deadline.

Do you take equity instead of fee?

Fixed-fee or retainer for most engagements. Equity on a small number of early-stage builds when timing is right. We do not lead with equity offers and we will not skip discovery week even for equity work.

Related from Resser

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