I am not sure I understand the prices for EC2 instances.
Amazon writes:
Pricing is per instance-hour consumed for each instance, from the time an instance is launched until it is terminated.
So I will get billed for 100% a month, unless I terminate this instance completely and lose all the data on the instance-store? This confuses me, as the Amazon cloud is said to be a cheaper alternative. But for a Large instance I end up with about $250/month, which is quite expensive compared to other, non-cloud companies.
you will be billed 24 instance-hours per day if your instance (server) is online 24/7.
This is exactly the same as Windows Azure Web instances.
The be billed just for what I use, it's more about Files and Database, as the server should be always up and running.
If you compare VPS hosting companies with this prices, you will see Amazon/Windows are cheaper, keep in mind that you will have remote access to that server no matter what OS you are using (windows or Linux distro).