I recommend reading the book "The Book on Investing in Real Estate with Little or No Money Down" by Brandon Turner and published by Bogger Pockets.

We also have been in business 20+ years locally and have 100+ Google Reviews accompanied by Yelp, Angie's List and Facebook reviews also, along with many local charity projects published in local newspapers.A company with this much good publicity is easy to gauge and justify the 50% deposit. 

@Lauren BishopI've recently published a write-up on Reddit.