Actually when I post Facebook ads to try to find cash buyers at least half of the people who come to my website want to buy a house to live in. The vast majority say they are cash buyers. If you were targeting Lease Option buyers with a little tweaking of your ad directly at that market you should have a tremendous response. Also Investor Carrot has a website specifically for this type of buyer.
In Panama, there are specific facebook pages for property sources. A free post on there leads to many tenant inquires. Plus I can quickly spot motivated sellers then contact them directly without spending a penny on marketing.
Perhaps starting a property for sale and/or rent site for your target area would get motivated sellers or landlords to post their deals on the site (for free) then you will be the first to know about these. it will be free advertising for you!