How can I calculate costs of deploying 1000 instances of Drupal? What are the things that should I investigate for making an estimate of the cost of deploying 1000 instances of Drupal, for example?

I was thinking in:


Database space
Database usage (in ops/second? how can I test it?)
Application uploads space
Application processing time (again, how to measure?)
Bandwidth usage (for medium/low traffic sites)
DevOps / Technical Support time


This is all about bringing a SaaS platform. Is there anything else I should take in consideration?

How can I know how many "instances" would be able to run in a single host? Much like a Shared Hosting

Would Amazon EC2 / Google / Azure be cheaper than having dedicated servers?
In reply to 'Would Amazon EC2 / Google / Azure be cheaper than having dedicated servers?'

I've done a lot of investigating into this and in every case they are NOT. 

80 Linux servers running 24h/365 - annual cost:
        Total cost per year
Google  £37,515.46
AWS     £29,196.53

These costs do NOT include data transfer.

You can buy a dedicated cloud appliance for less than £50k, fully supported, that will run more servers and last you 3 years (min).