The only way to find a buyer for your wholesale deals is to know if they are really a buyer or just a player.
To know if they are really a buyer you are going to have to do some research to find out if they have bought the type of property you have under contract to flip in the last 6 months, within a tiny radius of distance of your subject property and if this a second house they have purchased (ie not their primary residence, so they bought it as an investment)
The best source for researching this is again http://www.listsource.com