I got a whopping 496,000 coins as a reward!!! Are you kidding me? I used 2 count them TWO CASH FACILITIES and all I was rewarded was 496,000??!!
I have NEVER had a quest that paid less than 4,000,000 coins. Of course, it helps that I have a "Quest" farm with almost all of the crops that are 1 day or more, the main flowers, and trees. If I need a crop, I rarely have to wait for it to grow. The longest wait is for the factory production.
A lot of my neighbors have quest farms. Stop by my farm 13 and see how I did mine.