Before a single ringgit or dollar leaves the budget, ask one question: which recurring workload, done by people today, would move if a model handled it? If you cannot name that workload in one sentence, you are not ready to buy — you are ready to think.
A defensible case has three parts: the hours and cost of the work today, a realistic share that AI could absorb, and a payback window your finance lead will accept. The trap is inflating the share. Models do not remove work; they shift it. A 30% reduction that holds for twelve months beats a 70% claim that collapses in quarter two.
The proof is not the business case — it is the month after. Compare two consecutive months of the same workload. If the one line that moved matches the assumption in your case, you have signal. If it does not, you have an honest correction before the spend compounds. That is the difference between an AI decision and an AI hope.