I'm starting to systematize my fledgling real estate business so that I can scale it in the coming years. Listed deals in my area almost never pencil, so I'll eventually need outbound marketing to scale. I'm debating whether to build or buy my marketing data , and I'm leaning toward build for a few reasons, but here I'll focus on the economics. Can anyone experienced with outbound list-based marketing help me better understand the economics or if there's a different/better approach or provider (I used listsource as my reference example)? I do plan to initially use a list provider for proof-of-concept, so my question is about the long-term.

Since list providers charge for usage, they seem to exhibit diseconomies of scale and I worry that will limit growth in the long-term. When pulling sample lists, the juiciest data is very expensive and leads to a cost decision between highly-targeted small list or poorly-targeted large list, each of which is likely to yield few deals. Let's say the list provider has 50 criteria - my marketing budget would fund a list with 1000 targets across 3-4 categories or 200 targets across 6-7 categories. I'd like to be able to target across all 50 criteria and also to experiment with different levels of targeting. If I build my lists in house, this would be a one-time fixed expense and my ongoing marketing costs would be limited to direct outreach costs. There is also some data I'd like to use for targeting that just isn't available at any price if outsourcing. 

Can anyone with experience doing it yourself versus outsourcing comment on these and other tradeoffs?