Quoted from PinballBeerGuy:
Rather than compete with us on the open market, why don't you do like others have suggested and make friends with people in the pinball community in the area. Let people know what you are looking for and eventually someone will come back to you and say that they know someone who could use the money and would be willing to sell you the machine you are looking for a fair price.
This is the best advice. Almost all of my buying comes from networking.