I have a customer in town that has asked me to give a price on 5 different buildings in the last 30 years...each were a no go and I am really finding it hard to work up a price on the 6th.
Is he a customer or a prospect? I had a guy I did 1 small job for when I worked for someone else. I priced him a couple of other jobs for the employer, then later priced 2 jobs for him when I was on my own. All the quotes were too high for him. He was also a guy demanding I take my shoes off. I would take at least an hour looking things over, 1/2 hour answering his endless questions, 1/4 hour listening to him pitch his own business (photography) to me. I would get back to him next day with a quote and answer more questions about why so high, then him try to sell me family photographs, etc. Last time he called, I told him I was busy. I would not mind so bad if I were getting any paying business from him.
If this guy has never paid you for any work, he is not a customer. He is a tire kicker. For some reason, he likes having your bids as references but he always gets a cheaper one. In fact, it could be a game for him to award bids to his BIL or some other favored party. He gets a couple of bids, then tells BIL to bid $100 cheaper.