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The Business Case You Should Write Before Any AI Tool Purchase
By Nigel Guy · 2 min read
The usual path into a new AI subscription is a demo, a colleague's
recommendation, or a feature list that sounds useful. Two months later you're
either quietly still paying for something you barely open, or you've
cancelled without ever finding out whether it actually helped. Neither
outcome tells you anything, because nothing was measured going in.
The rule: before you pay for any AI tool, write down what you currently do
without it and what that gap actually costs you — the subscription is only
worth it if that cost is real and bigger than the price.
The mechanism: the Displacement Test
- Name the specific task list, not the category. Not "content
creation" — "drafting the weekly client update" or "first-pass replies to
support tickets."
- Cost what you currently spend doing that task without the tool — time,
error rate, the other tools currently patched together to manage it.
- Add the full cost of adopting the new tool, not just the subscription
price. Time spent learning it, migrating data into it, getting a team
actually using it rather than reverting to the old habit.
- Set a trial window and a specific number you'll check at the end —
"cut drafting time by half" or "handle twice the ticket volume without
adding hours." Not "see how it goes."
- Check with whoever actually has to use it before you buy, not after.
A tool that's a good fit for you but that your team quietly won't adopt
is a cost with no offsetting benefit.
What to skip
Skip buying because a competitor or a well-known account uses it — that's
not evidence for your specific workflow, only for theirs. Skip letting an
"annual discount ends today" prompt push you into deciding before you've run
the trial window you set. A tool worth having on an annual plan is worth
having on a monthly one first.
Guardrails
- This guide can't verify a specific vendor's current pricing tiers or
feature claims — check the vendor's own current page before you commit,
since these change often.
- It doesn't cover procurement, data-security review, or compliance sign-off
that a regulated business may need on top of this — treat this as the
commercial half of the decision, not the whole one.
- The trial result is only honest if you set the metric before you start
using the tool, not after you've already decided you like it.
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