Business analysis is bought separately and paid for on its own, with no obligation to buy development from us. That is deliberate: an estimate produced by the party who also wants to build tends to be optimistic.
From your side we need one decision-maker and access to the people who actually do the work. The time cost is usually six to ten hours per key person, split across interviews and two review sessions. Most wrong assumptions come from asking a manager how the process runs rather than the person who runs it every day.
The estimate arrives only at the end of the analysis. Before that nobody has enough information, and a number given at that point is a sales argument. We estimate the whole delivery chain — analysis, design, development, testing, project management and meetings — because overruns almost always come from having costed only the time spent writing code.