Ballpark cost for webserver with 1M visits/month

For a simple database web application on AWS or other cloud services, how much would be the ballpark cost/month if I have say 1 million and 10 million visits per month? It's mainly a text-based website on an SQL query, no significant photo or video traffic.

I find it difficult to estimate the cost, as I don't know if I'd need a micro or large server, how much the auto scaler is etc. Would appreciate any ballpark figures or rules of thumb.