10k, really?
Not that I fully understand how your theory works, but 10k isn't going to get you an inch off the ground if you want enterprise class gear.
Unless you don't believe in speed, reliability and redundancy.
I don't make things up :) And we always put 2 in for redundancy!
Here's some CoLo prices, too:
http://www.redstation.com/colocation.html
So, figure at least £1400pcm for a single rack in a single data centre. There's probably loads of extras you'll need too.
But whatever, Pete - we clearly disagree on a number of things such as "industry standard" and "world class".
Well, firstly, I don't believe you can run something that big on rented hardware. Facebook has over 800 million users.
Let's say you store just 500 kilobytes of data per user. That's
800,000,000 * 500 = 400,000,000,000 kilobytes.
400,000,000,000 kb = ~372 Terabytes of storage alone.
Secondly, even if it as all rented and managed by someone else - you're still going to pay for it!
I just think Pete's got his head in the clouds on this one.