Capitalisation of maintainable earnings as the workhorse method at this size, cross-checked by discounted cash flow, comparable companies and precedent transactions - with the normalisation schedule shown line by line, so you can see exactly how the range was made.
Fixed fee - quoted before we start
Standalone, or as an assessment extension. Two to three weeks, and the fee never moves after the quote.
This is an indicative desktop range for you alone - not a formal valuation for financial reporting, tax, litigation or fundraising. The engagement letter says precisely what it can and can’t be used for, because a number you can’t defend is worse than no number.