After looking at your requirement i believe you shouldn't go for Amazon EC2, as it will cost you little higher. Buy a dedicated sever as per your budget from "single hop". They are very Good in service, Communication and support.
That'd use up about 240GB of bandwidth a month, so assuming one of Amazon's micro instances you're looking at something in the region of $50 per month.
Is your site static or dynamic? If it's all plain HTML files and such, virtually any shared host or even a CDN that supports on-CDN storage (if you want geographical targetting) would be a better choice.
I've used both Amazon Web Services and Storm Server for my business and they are both excellent.
For your case I would recommend going with Storm Server with 5 cents per GB of bandwidth per month. With AWS you pay 12 cents per GB.
With storm you can also run WHM/cPanel and make your life easy. With AWS, you're pretty much on your own. Gota be a geek figuring stuff out.
All the best!
██ We Have Generated Over 7 Million cPanel Backups Come Dance Together With Us Y'all!
██ Offer Your Own Backup Hosting Service - SiteAutoBackup.Com (Private Label / WHMCS Ready) ██ WebHostingBusinessBook.Com | YouTube.com/WebHostingTutorial | NowOpenOnline.Com