Know your niche - the mother daughter stuff is good and sells well to the right traffic - but then so do most micro-niches - with "the right traffic" being the key.
If you decide to build your own pay-site, start building traffic now. Create a few blogs/free-sites/legal-tubes etc in that niche and promote existing programs while you build traffic. If you can create enough niche traffic to make money, then build your own site and start directing the traffic to that site.
if you can't make money promoting the niche - don't invest heavily in it.
just my
