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We Got Wildly Different Quotes for a Custom AI Assistant. What Actually Drives the Development Cost?

Quotes for a custom AI assistant vary because suppliers imagine different products. We explain the cost drivers and write a scope that makes quotes comparable.

Updated 3 min readBy SpiderHunts Technologies

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Quick answer — TL;DR

Custom AI assistant quotes differ because each supplier is pricing a different product: different data connections, different levels of testing, different security and different support. The cost is driven far more by integrations, data preparation, evaluation and ongoing running than by the AI model itself. A written scope that pins those down makes quotes comparable.

Three quotes, three different worlds

You asked three suppliers to build an AI assistant for your team: something that answers questions from your documents and can look things up in your CRM. One quote is small and promises a quick turnaround. One is several times larger. The third is somewhere in between and full of terms you do not recognise. All three say they will use the latest AI models.

You cannot tell whether the cheap one has missed something or the expensive one is padding. The proposals describe different things in different language, and none of them quite matches what you had in mind. Choosing on price feels risky; choosing on the most confident sales call feels worse.

Why the quotes vary so much

"An AI assistant" covers a huge range. At one end is a chat window connected to a folder of documents using an off-the-shelf tool. At the other is an assistant that signs users in, respects who can see what, connects to several live systems, is tested against hundreds of real questions, logs everything, and is monitored and maintained. Both are honestly called a custom AI assistant.

The AI model itself is rarely the main cost. The work is in everything around it: getting your data into a usable state, connecting to your systems, making sure people only see what they should, proving the answers are good enough, and keeping it working as models and data change. Suppliers make different assumptions about each of these, often without saying so.

The drivers behind the numbers

Cost driverWhy it moves the price
Data sourcesEach system (SharePoint, CRM, ERP, database) needs its own connection and upkeep
Document conditionScanned, duplicated or messy files need cleaning before AI can use them
PermissionsMaking answers respect who can see what is significant work
ActionsLooking things up is simpler than updating records or sending messages
EvaluationA proper test set of real questions takes effort, and is what makes quality measurable
Security and hostingPrivate hosting or strict data rules add design and running costs
Support after launchMonitoring, model updates and improvements are ongoing work

A low quote is not necessarily wrong. It may be for a simpler product that fits your need. The problem is only when you cannot tell which product each quote is for.

How we help you get comparable quotes

Whether or not we end up building it, we help you pin down what you are buying.

  1. We work through the questions the assistant needs to answer and the actions it needs to take, using real examples from your team.
  2. We list the data sources involved and check their condition and access routes, so nobody is quoting blind.
  3. We define who can use it and what each person is allowed to see.
  4. We set out how quality will be judged: a test set of real questions with agreed good answers, and the standard the assistant needs to reach before launch.
  5. We state the hosting and data handling requirements, including anything your clients' contracts demand.
  6. We describe the support you expect after launch, so running costs and maintenance are priced rather than assumed.

The result is a written scope any competent supplier can quote against. It also tends to show whether a simpler, off-the-shelf option would do, in which case we say so.

What you get from this

Quotes you can put side by side, because they answer the same questions. You can see whether a price difference comes from a different approach to testing, a different hosting choice, or simply different rates.

You also go into the build with a shared definition of done, which is the thing that most often goes missing on AI projects and leads to arguments later.

And the test set outlives the buying decision. Whoever builds the assistant can use it during development, you can use it to accept the finished product, and it becomes the check that shows whether later changes made the assistant better or worse.

Is this your situation?

  • You have quotes for a custom AI assistant that differ widely.
  • The proposals describe the product in different terms.
  • You are not sure which data sources and systems need to be included.
  • Nobody has defined how the assistant's answers will be tested.
  • You want to understand the cost drivers before committing.

FAQ

Frequently asked questions

The questions readers ask us after this guide.

Still have a question?

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Is an off-the-shelf assistant cheaper?

Usually to start, and sometimes it is all you need. Custom work makes sense when you need specific data connections, permission handling or behaviour that products do not offer.

Why do you not publish a price?

Because the drivers above vary so much between businesses that any single figure would mislead. A clear scope gets you a real number.

What are the running costs of an AI assistant?

Model usage per question, hosting, search indexing and maintenance. Usage costs depend on volume and on how much text each answer needs to read.

Can we start small and extend later?

Yes, and it is often wise. Starting with one data source and one group of users gives a real test before you invest further.

What do you need from us?

The quotes you have, a list of the questions and tasks you want covered, and an overview of the systems involved.

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