Why two quotes for the same system differ several times over

Collect three quotes for the same internal system and the difference between them is frequently not percentages but multiples. The first thought is usually that somebody is inflating a price. In practice something else is almost always true: three suppliers answered three different questions, because the request allowed them to.

In short

• The difference is usually not in the price but in the scope: what is included, what is assumed to be your work, what is deferred to a second stage.
• Three things create the largest gaps: data migration, roles and permissions, and integrations with what is already in use.
• If the request does not say what happens to existing data, every supplier guesses differently.
• The cheapest quote is usually not a different solution but the same solution missing half the work.
• What makes quotes comparable is not a more detailed specification but identical assumptions.

The three things that create the largest gaps

First, existing data. A system is rarely built on empty ground: customers, orders or contracts already live somewhere, frequently in spreadsheets. A supplier who included migrating and cleaning them will look more expensive than one who quietly assumed you would type them in. Both can be honest; only one price contains work the other does not.

Second, roles and permissions. "A system for staff" can mean one shared login or five roles with different visibility and an approval flow. This is one of the largest cost differences and one of the least often written down, because to the buyer it feels self-evident.

Third, integrations. If the system has to talk to accounting, a warehouse or a shop, that is separate work with its own risk and often a dependency on a third party. A quote where integrations are "planned for later" is not cheaper — only deferred.

What is usually missing from every quote

• Who prepares content and initial data, and by when. This is the most common cause of delay, and it almost always sits on the buyer's side.
• Who decides when two departments produce contradictory requirements.
• What happens after launch: who fixes faults, who trains users, what that costs.
• Where access lives and who will hold it when the project ends.
• Which part of the work is one-off and which is ongoing. The ongoing part is worth knowing before, not after.

How to make quotes comparable

A more detailed specification helps less than expected here — it mostly makes the document longer. Something else works: a single page of scope summary, sent to everyone, stating assumptions rather than features.

• Who will use the system and how many distinct roles there are.
• What data already exists, where it lives, and who will move it.
• What the system must connect to, and whether access to that system can be obtained.
• Which result counts as the first usable one — not the final one, the first that can already be used.
• Who fixes faults after launch and who trains users.

With that summary, three quotes suddenly describe the same thing, and the difference between them starts to mean what it should mean: a different way of working rather than a different understanding.

Where this topic ends

If you are collecting quotes for a business website rather than an internal system, the questions differ — there, what a proposal must contain matters more than why prices vary. That is a separate subject and we have a separate piece for it. This one is about custom systems, where scope is driven by roles, data and integrations.

Illustrative scenario, not a description of a client project

Imagine a request saying "we need a system to manage orders". One supplier prices a simple list with a single login. A second prices the same plus three roles, because experience says that is how it goes. A third also includes migrating data from spreadsheets and connecting to accounting, because they asked. Three prices differ by multiples, and all three are correct for their scope. The only thing that was wrong was the request. This is an example of how we weigh scope, not a promise about price.

A practical check before choosing: ask each supplier to write one sentence describing what their quote does not include. The answers will differ more than the prices, and that will be the most useful information in the whole process.