I obtained the 1er I drive today via a dealer search. It was done willingly, no hassle, no cost, and the SA and I found the one I wanted. It was in the port in Vancouver, and the local dealer talked to dealer who owned the car, it was an "inventory" car (ie not sold) and my dealer was able to get it shipped to this dealership instead of the ordering dealer. No problem. I paid an extra couple hundred for "extra shipping" and I was OK with that in that it avoided the long wait time of an order (which was the next choice). I did not pay any deposit. I paid for the car when it was delivered to me.
I do have some sympathy for the dealer in the OP's case, as it seems the OP was there 3 times without doing a deal, and the dealer might reasonably be cautious in asking for a deposit to show "intent". Dealers do get abused on occasion, not saying necessarily in this case.
2016 340i xDrive MPerf. EBII
Previous BMWs - 18 others since 1971.