Very simple equation my friend: hours spent making the bot * hourly rate.
The total depends entirely on the complexity of the request.
The total depends entirely on the complexity of the request.
Unless you are a brand and can charge whatever the fuck you like for your work — things typically have a cost. You know how much a cup of coffee costs, a laptop, a car, a house. Chatbots and web-pages have their market price as well.
(And FWIW, I don't know, maybe it's ok kinda price in USA, but to me all this doesn't sound like a $5000 deal.)
You are thinking that people charge some amount derived from their costs. But it's more like people charge as much as they can (as the market allows) and the actual costs are only important as a lower bound - there is no higher bound.