Hiring an app developer is like booking a cab.
If you give the cabbie clear directions, ask questions, and find out upfront what the cost of the journey will be, you generally get what you want – you arrive on time, and pay fee you agreed at the start of your journey.
If you keep changing your mind, give unclear directions, and don’t know the exact address, so you have to ask the cabby to drive up and down the street while you look for it – the cost of the journey mounts up.
If a cab offers to take you somewhere for a much lower fare than the other cabs, the question you should ask is “why”? What corners are they cutting?
If a cab looks beautiful, and impresses you with the polished chrome work of the car, the smartly pressed uniform of the driver, and the expensive leather interior, you should ask “how much is this costing me?”
Be clear. Demand clarity. Agree the cost up front.