Building a cloud storage server?!?

I have been wondering, and found i have no idea where to begin..

So as most of you would agree / see the world is becoming more "cloud storage". 

and i use it like crazy i have close to 2TB in cloud places.

One of my main concerns is the Data could be lost, drastic example but google falls apart over night all servers

stop,all my Drive Docs (mostly work and back up) would be gone. 

i am competent building and tinkering with a PC, but never in my life thought or worked with a server.

 What i was wondering was.

Firstly how feasible is it to build a "cloud" storage server?

would you consider buying one over building?

 are there any neat hacks to turn a cheap external into one?

have any of you done this? 

Just get a VPN up and running then map that drive, it is the what I have it setup

I am already maxed out on my current ones.

should of mentioned looking for 10+TB 

Build yourself a file server, get a couple of raid controllers and go from there

i have a lot of reading ahead of me.

thank you ^^