Evaluating Amazon EC2 for a new startup

Recently I got involved in shaping up a new job portal site. While architecting the application I was sure that it will be best to go for Amazon S3(Simple Storage Service) for storing my unstructured data in forms of pdf, word-docs, ppts. When I started thinking upon deployment options I started digging into Amazon EC2 . This was some interesting thing that I want share about..
We were very clear about our plan. The steps till final release we defined were 1) nightly build release 2) alpha release 3) beta release

Nightly build release is just for developers and testers. alpha release is going to be accessed by some real market users ( a trial access invitations being sent to few top recruiters in US market) and once its accepted by industry then beta release with some marketing. Plan was to have 500 odd recruiters and 5000~6000 candidates in first 3~4 months, which was very modest. But We wanted to keep the application scalable and our deployment architecture such that we can go and keep adding city after city ..Boston..Chicago..NewYork..and so on.. the way craigslist done !

After so much of buzz of "cloud computing" , adding up of Elastic term by Amazon I seriously started looking for it.. claims are really promising.. you are paying only for what you are using and you can scale it factor-n without any hassle and very rapidly.

Big question for us was whether to go for EC2 service from day one? Will it be cost effective from day one?

I started searching answer for these questions.. I revisited pricing of Amazon EC2.

The pricing below is based on data transferred "in" and "out" of Amazon EC2.

Data Transfer In
All Data Transfer	$0.10 per GB

So I am going to pay $0.10 for every GB starting from my first byte. When I requested for some quotes from hosting service provider for dedicated server , I got response with quotes ranging from 5$ to 75$ per month with 1500 GB bandwidth included.
It was appearant that if my bandwidth usage is going to be above 500 GB but below 1500 GB then dedicated server is the best bargain for me.. but the day I start consuming more than 1500 GB bandwidth amazon Ec2 would turn me cheaper and also very scalable solution..

Decision was obvious start with a dedicated server and switch to EC2 when you are real candidate for it.. when you really are a growing and scaling application.

So take a pill only when you require it and if you require it :)