Stockton 12 Honda

Unfortunately, I had a very poor experience with Stockton 12 Honda today. My salesperson was very nice at first and showed me a couple of vehicles that I was very interested in leasing (at least one vehicle and possibly both.) I have excellent (800+) credit and I was willing to pay a large down payment (up to $6000 cash.) However, when I asked how much it would be to lease the vehicles, I was told that I could not be given that information without signing a "commitment to buy" contract. I said that I could not would not sign a contract that committed me to buy a car without knowing how much it would cost per month. However, they told me that that couldn't give me numbers until I signed the paperwork stating that I would purchase the vehicles. Is this how car dealerships do business these days? How can I commit to purchase something before I know how much it will cost? I left the dealership very confused. I am hopeful that their competitors don't do business like this.