My main business is in finance, so I rent data center space primarily in chicago, nyc area (mostly north jersey), virginia and los angeles. The minimum lease is 4RU, but I end up using a 1U server and a 1U 10/40GbE switch (the switch takes up half the depth, so i stick an ethernet router behind it), leaving 2U unused.

I had a failure once (on an iMac with a seagate 1TB hard drive that was later recalled) but since I had a local backup I didn't lose anything.

I started exploring solutions and realized that, since I had space, I could spend a few grand and get a barebones server with a few hard drives and stick it in space I'm already paying for.

This turns out to be really convenient, especially since technicians at the data center can do basic maintenance work (like hot-swapping drives) for you at a reasonable rate (generally 100-200/hr, billable in 15 minute increments; you ship them the drive and they do their magic).

In terms of absolute cost (not counting cost synergies due to leveraging the business space), each 4U lease runs from 100-500/mo with 10Mb internet (which is not bad for backing up small amounts of data; for larger amounts, shipping drives or just driving back and forth is faster and easier). Yes, dropbox is dramatically cheaper, but this way I have much more control over what's going on.