Buy the bottom of your traffic, taking Google content network as an example, you're paying $100 a day to advertise on a site, its backing out to a nice $200 a day, you know 65% of the spend is going to the site owner, use those figures, calculate how much you think the site is worth and buy it.
As you control the end-to-end analytics e.g (Google SERP>Site>Landing page>merchant) you know which traffic is ultimately backing out into the leads/sales, use this data to optimize the funnel.
Pay the investment off quickly by increasing the sites revenue by 300% - 500%.
Repeat.
Hey - At-least your investing into what you know and not getting sidetracked learning about real estate, gold prices, forex and wall street.