Buying a truck, frustrated

Why is it that these "salesmen" are refusing to give me a price and always asks when I want to come in? Why can't we set up the deal through e-mails? I already qualified for 0% apr, I have the money for down payment, I just need them to structure the deal. Instead they do everything to avoid selling me the car. "how much do you want to pay a month?" "do you have a trade-in?" …. Do these tactics work on people? Seriously? What does it take for them to be honest and structure a deal through e-mail?