You can target lists through a multiple list source sites, skip trace those lists, then market to those buyers through cold calling, SMS campaigns, direct mailers, and/or door knocking; amongst other routes.

@James Wise MICHIGAN UPDATE: new law went into effect January 2, that landlords can no longer discriminate on tenant income source.

I consider the two best sources is from other trusted contractors and other RE investors.  

Build - rent - refinance -repeat. in columbus ohio you are buying old houses that are 1900 or 1920 or 1940 and you are in a sellers market. on the other hand you can source land which is a buyers market and build single family homes or duplex or triplexes that will return by renting and pulling cash out on a DSCR loan and doing it again. there aren't a lot of strategies that do this. flipping is different. so many risks. but when someone has a well oiled machine it's all good and less risk.

Still plenty of good deals to be found, just need the right people in place to help source and rehab.

-  we use various sources (Web, Facebook, click funnels, etc. to fill up the PONDS for our investors and wholesales to fish from.).  

If you do have money to invest in your wholesaling business, then you can pull lists from Prop Stream or List Source and skip trace them, use bandit signs, social media advertising, Google/Bing ads, Direct Mail, etc.

You could pay the contractors but if you can be a strong referral source I'm sure they'd be happy to give you estimates.

Or there can be being a GP in a syndication, where you have, effectively, no money down: source $3mm deal, commit $50k with your LPs, collect 3% acq fee ($90k) without ever funding your $50k... you pocket $40k, and have a $50k interest in the deal. 

I recommend focusing your attention on sourcing great real estate rather than allowing the creative financing be the tail that wags the dog.