flipping reo without end buyer going around you

If you find a good deal on reo listed with realtor,or,property realtor just starting to list,if you get a price thats good for you,how can you flip it to end buyer without them going to realtor and making their own offer,or even show the house without it leading to bidding war?Example,if I find a home I can get for $50000,home is worth $90000,and I think I could sell it for $65000,how do you keep your end buyer from going to agent and offering $55000,agent makes more,plus buyer saves money,THANKS