Advertising is salesmanship multiplied by reaching more people via targeted direct mail, or other media whether online or offline. 

I should make $15,000 and the flipper could make between 40K and 50K. ...With a spread that large, most wholesalers would suggest you follow the advice in my previous post in this thread. 

I have thought a new service which could offer landlords cash to spread the cost of big ticket expenses over 10months.

It may be just as the article says and will come down to a lower level, $200 million or so and be spread out over several years.  

Other areas are more spread out where there are only a couple 2-4 unit properties and they attract people that can't afford to rent a SFH.  

Sending out hand written personal letters, adds on social media, newspaper, craigslist, handing out business cards and posting signs out.

If you want to be added please send me a message and lets set up a time so you can give me your specific requirements (area, price range, spread, etc).

Some markets are more desirable (say where you can rent a home for 700 and the lot rent portion is 300, and you have a good spread).  

They charge fees so there will have to a big enough spread for you to make money.

For profitability I like this spread sheet.