David Umanzor is an Uber driver in Washington, D.C. Part of the time he's driving, he's scouting properties for an investor, Daniel DiGiacomo, who has been flipping homes for a decade, but has never seen the market this tough.

"With the prices as high as they are now, the margins on our flips are pretty slim," DiGiacomo said.

Competition is fierce among flippers, because the returns are falling, hitting the lowest point in eight years during the first quarter of this year. Nationwide, flippers saw an average return on their investment of about 39% during the first three months of 2019, down from 42.5% in the previous quarter and nearly 49% a year ago, according to Attom Data Solutions. The number of flips are down 8% annually, so the stakes are up.

"Investors may be getting out while the getting is good, before the market softens further," said Todd Teta, chief product officer at Attom Data Solutions. "Gross profits and ROI are starting to weaken and the number of investors that are flipping is down 11% from last year."

Precisely why DiGiacomo has hired about 150 Uber and Lyft drivers to scour the streets for opportunities. It's his way of getting ahead of the competition in a larger geographical range.

"The best deals are always the deals that we put our eyes on, and I can't put my eyes on every single deal, so Uber drivers are out there, they're looking at all kinds of different neighborhoods, they're putting their eyes on many houses, and if they see something that we've talked about fits my strategy then they send it over," he said.

DiGiacomo used to go to auctions, but he says there are too many bidders there now, driving prices even higher. As for regular property listings from real estate agents, low mortgage rates have too many regular buyers competing with him. That's why he'll pay a driver $500 for a lead that turns into a sale. So far this year he says his team of 150 drivers has put in about 2,200 leads, and he normally closes about one deal per 100-150 leads. Overall, he makes about 15 deals a year.