Everyone wants to become a listing agent and that is their priority but I like to think Buyers are valuable to and can lead to listings.
What are the characteristics of your Buyer -- they want a __ bedroom, __ bathroom, __ square foot home in a particular neighborhood. Take the physical characteristics to your data source. Title Companies are great at this and get your farm -- it may only be fifty records or hundreds, regardless -- it is a very defined targeted farm.
Your job should be to put a letter together that says, "Hello my name is ___ and I have a buyer interested in your type of property. Your __ bedroom, ___ bathroom, ___ square foot home that you purchased on ___ is something that my buyer might be interested in looking at.
Please contact me or I will be in contact with you over the next couple of days.
Then FOLLOW UP -- put other post cards out -- door knock -- do whatever it takes -- maybe, just maybe one of those properties in your farm will want to sell -- how about that, a double ended deal might be possible.
Plus, you are doing everything in your power to meet the needs of your buyer and earning your commission.
Don't forget the power of personally addressing the envelopes or personally putting a stamp on the envelope == it won't look like junk mail and get tossed.
You will make an impact and promote yourself along the way. Make it a profitable day!