The way I use to do this in Austin Texas...
1) Pull the property tax records for your county.
Usually you can purchase a physical CD with data for a few $100.
I use to purchase these every quarter, as #2 will change each time a property sells (tax data changes).
2) Lookup turnover threshold for your area.
Last time I did this in Austin, 3.2 years was normal threshold where people moved.
After the Houston flooding, it's anyone's guess how this number might work. Likely you'll have to come up with some other way to analyze data + I'll continue on about how I did this in Austin.
3) Start sending monthly letters to people who's tax bill address + property address are the same (owner occupants) providing them tips for staging their house for sale + providing coupons for local people to do staging work, like repairs + landscaping.
Also include a coupon for using your site at a discount to list their property.
Keep sending to these people, until they use your service (numbered coupon, so you can track them) or the property sells (property tax data changes).
4) There are many other strategies you can use with this data also.
For example, properties with common tax bill addresses are rental properties. You can stripe these (organize them into buckets) like between 2-5 properties or 6-10 properties.
Each bucket has a different marketing approach.
All sorts of imaginative ways to market to these people.
5) I share this technique with every realtor I meet.
So far no one has every used this technique, that I've told.
You're welcome to call me to talk more about this, if required.
I'm way out of Real Estate, so happy to share anything about this your like.