To the OP I am in the home building and remodeling business. And for some reason this all about the dollar. Customers says i can get it done cheaper. My repose is I use middle grade products with good quality Labor. Also i will ask how many bids are you getting and if more than three i will not waste my time on bidding it out. Because these customers are looking for the cheapest price and person and in the long run will be hard to satisfy them.
I have a saying If I can not make money on a job, i might as will go fishing. because if i go fishing i will lose $2.50 (the cost of worms). If i under cut or bid to low it could go into the thousands.