There is no single figure, because several pricing models coexist in the market.
Four models
Free when the same contractor will do the work — the usual arrangement on private jobs, sometimes charged but credited against the contract if the client proceeds. A fixed fee per project. An hourly rate, useful when the scope is unclear or someone else's estimate has to be checked. A percentage of construction cost, on larger projects — ask what the percentage is taken from.
A "free" estimate is not free. The hours spent land in overheads; if you produce many estimates and win few contracts, that line grows quietly.
What drives the price
Whether a building project exists, the level of detail required, whether a certified signature is needed, the deadline, and the size and type of the object.
Questions to ask first
What is included — does it cover site measurement? What format will you receive? How many revisions are included? Will a certified specialist sign it? How long do the prices hold?
For small jobs you will carry out yourself, the Excel template or the online generator is faster than outsourcing.