"Spoken like a true used car salesman."
Here's the way it works:
Looking to buy? = There's a shortage. If he sells you this car it might be weeks before he can find another on to sell. The only reason he is willing to sell it to you for 25% over Blue Book is because he likes you.
Looking for a good trade in allowance? = There is no shortage. In fact they have more cars than they can haul to the auction where no one is buying anyway. The only reason he is willing to give you anything at all for it is because he likes you.