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?

Answer

Would you like us to write a business plan too or should we just plan a VC round? @chicks No I just want to know what variables should I have in mind to build my own business plan