Price the work, not the number of tabs.
Complexity comes from the operating logic, quality of inputs, number of entities and currencies, financing arrangements and intended use. A short model can require careful design; a large template may still leave important questions unanswered.
What your proposal should specify.
Agree the platform, forecast horizon, time intervals, input sources, outputs, scenarios and checks. Clarify the number of review rounds, handover, documentation, timetable, VAT treatment and how changes to the brief are approved.
Choose a proportionate starting point.
A simple receipts-and-payments model may answer a near-term cash question. A funding or acquisition decision may require integrated statements and more detailed schedules. Affordable modelling means choosing appropriate work while keeping material assumptions visible.
Separate delivery from maintenance.
A one-off build does not automatically include monthly updates or unlimited revisions. Discuss who will own the model after handover and whether ongoing support is needed. Reliable inputs and a clear brief can reduce avoidable rework.