How many servers? 1, 100, 1000,10,000? Where are you hosting them, in your home or in a datacenter? How much are you paying for bandwidth and power? What SLAs do you have in place for network and power? How much do you pay for your remote hands?
I hope you see what I'm getting at. While I love ZFS and think self-hosting can make a lot of economic sense, without knowing all the variables you can't really make a fair comparison.
I run Redundant disk controllers and hard drives on ZFS. And it's cheaper than a decent RAID system.
First thing I do with a new server is disabling RAID.