Glean vs Guru vs Notion AI vs Microsoft 365 Copilot vs a Custom Knowledge Assistant: What a 50-Person Company Pays in 2026

Short answer: for a 50-person company that wants staff to ask questions and get answers from its own documents, Notion Business costs $12,000 a year ($20 per member a month on yearly billing, with Notion Agent and Enterprise Search in beta), and the Microsoft 365 Copilot Business add-on costs $10,800 a year at its current $18 per user a month, or $12,600 at its regular $21, on top of a Microsoft 365 Business plan. Glean and Guru do not publish prices: both ask you to talk to sales. A custom knowledge assistant built around your own documents and systems costs $15,000 to $50,000 once, plus model usage and hosting. On published prices, a $15,000 build matches three years of Notion Business at about 21 users, and a $50,000 build at about 69 users. Every vendor price below was read from the vendor's own page on 12 October 2026.

One date matters if you are pricing Microsoft this quarter: Microsoft's business page says the Copilot Business discount runs from 1 July 2026 to 31 December 2026, and the add-on is sold only to existing customers on an eligible Microsoft 365 Business plan (microsoft.com).

If you want a range for your own build first, the AI development cost calculator gives one in about a minute.

The routes, with published prices

Notion's page shows yearly billing by default and says yearly saves up to 20%, so the monthly-billed price is higher than the figure above. Microsoft's add-on requires an eligible Microsoft 365 Business plan, which is a separate cost if you do not already pay for one.

The arithmetic for one company

Take one company: 50 people, all of whom would use the assistant.

Per year. Notion Business is $20 x 50 x 12 = $12,000. The Copilot Business add-on is $18 x 50 x 12 = $10,800 at the discount and $21 x 50 x 12 = $12,600 at the regular price, assuming you already pay for Microsoft 365 Business. Moving everyone to Business Standard with Copilot is $23.50 x 50 x 12 = $14,100, and Business Premium with Copilot is $32 x 50 x 12 = $19,200, both including the Microsoft 365 apps.

Over three years. Notion Business is $36,000, and the Copilot add-on at the regular price is $37,800.

Where a custom build breaks even. One Notion Business seat costs $720 over three years, so a $15,000 build matches it at about 21 users and a $50,000 build at about 69 users. Against the Copilot add-on at $21, the crossing points are about 20 and 66 users. These are KUMO's calculations on the published prices above, and they leave out the custom assistant's own model usage, hosting and upkeep, so treat them as the earliest a build could break even.

The seat comparison is also not like for like. Notion Business is a whole workspace and Microsoft 365 is your office suite; a custom assistant replaces neither. Seat cost alone rarely justifies building. The companies that build usually do it for one of the reasons below.

When each route is the right one

1. Your knowledge already lives in Notion: turn on Notion Business. If the wiki, the process docs and the meeting notes are in Notion, its own agent reads them with the permissions you already set.
2. Your company runs on Microsoft 365: price the Copilot add-on first. Copilot works inside the documents, mail and Teams chats your staff already use, and the discount makes 2026 the cheapest year to try it.
3. Your knowledge is spread across many tools and you have 100 or more staff: get Glean and Guru quotes. Both are built for large connected estates, and Guru includes solution engineers to set it up. Ask each for a written price per user and the minimum contract.
4. The answers live in your own systems, not in documents: build. Order status, job history, policy terms, stock levels or customer records sit in a database or a system of your own, and a seat tool can only read what its connectors reach.
5. Who may see what is the hard part: build. When a branch manager, a contractor and a client must each see different records, the permission rules are the product, and you want them written in your code where you can test them.
6. Customers, not staff, will ask the questions: build. A seat tool licenses your employees. An assistant inside your customer portal or app is a product feature, priced by usage rather than by seat.

Comparing assistants that take actions, not only answer? Copilot Studio vs ChatGPT Business vs a custom AI agent prices that decision. For where answering ends and acting begins, see RAG vs AI agents for internal operations, and for where the data and model run, private AI agent deployment: cloud, VPC or on-premise.

What a Starter Build buys

A KUMO Starter Build ($15,000 to $50,000) is a launched first production version of one assistant: your documents and one or two of your systems connected, answers that cite the source they came from, your permission rules enforced on every answer, a test set of real questions your staff ask with the expected answers, deployment into your own cloud account and a handover another engineer can continue from. See AI product and platform engineering for how builds are scoped, and AI workflow automation if the assistant should also act on what it finds. KUMO's founders built Volopay's first production version as its founding engineers, a finance product where every approval and every payment had to be traceable, which is the discipline an assistant needs when it reads records people are not all allowed to see.

Costs after launch

Seat tools recur and rise with headcount and plan tier, and Microsoft's discount ends on 31 December 2026. A custom assistant has model usage billed by the model provider per request, hosting, a database or search index, monitoring and engineering time when you add a source or change a rule. Decide before you sign who owns the test set of questions and who checks answers when a policy changes; if you keep adding sources and features, the $5,000 to $10,000 monthly band applies.

How to get a real number this week

Write down three things: how many people would use the assistant, where the answers live today (documents, which tools, which databases), and the ten questions your staff or customers ask most often. With the first two you can run the arithmetic above for your own company. With all three, a free 30-minute call with an engineer gives a band for your brief.

FAQ

How much does Glean cost? Glean does not publish a price. On 12 October 2026 its pricing address led to its home page, which offers a demo rather than a price list.

How much does Guru cost? Guru does not publish a price. Its pricing page says the investment is tailored to your scale, knowledge complexity and AI maturity, and includes a team of solution engineers.

How much is Notion AI for a business? On 12 October 2026 Notion listed the Business plan, which includes Notion Agent, AI Meeting Notes and Enterprise Search (beta), at $20 per member a month on yearly billing. For 50 people that is $12,000 a year.

How much does Microsoft 365 Copilot cost for a small business? Microsoft 365 Copilot Business is an add-on at $18 per user a month paid yearly during the 1 July to 31 December 2026 discount, $21 regular, for customers on an eligible Microsoft 365 Business plan. Business Standard with Copilot is $23.50 and Business Premium with Copilot is $32 per user a month, paid yearly.

Is it cheaper to build your own AI knowledge assistant? Not on seats alone for a team of 20. A $15,000 build roughly equals three years of Notion Business at 21 users, and a $50,000 build at about 69 users. Below that, the reasons to build are answers that live in your own systems, permission rules that must be exact, and assistants your customers use.

Last verified 12 October 2026. Notion prices from notion.com/pricing (yearly billing view), Microsoft prices and discount dates from microsoft.com/en-us/copilot/solutions/business, Glean from glean.com, Guru from getguru.com/pricing, all read on that date. Annual totals, three-year totals and break-even user counts are KUMO's calculations on those published prices at the volumes stated. KUMO bands are KUMO's published prices.