I've spent the weekend playing with this.  It was actually dead easy - although I learned a lot on the way.  Price seems pretty good.  I'm using a small instance for testing ideas atm.  So I pay about 11 cents (US) per hour I actually use it.  I may have spent as much as two dollars over the weekend.  To have it permanently is about 70 dollars US per year.  That's essentially renting a single cpu box with Windows 2012 and SQL Express 2012 160Gig of disk.

Here are my steps.  I concentrate on stuff that's relevant to EC2 or it being a new machine with an operating system I have never seen before.  Google was a big help.

Setting up DNN on Amazon EC2/Server 2012/SQL Express 2012

 1.       Create an instance (outside the scope of this guide)

 a.       I chose Windows Server 2012/64bit plus SqlExpress2012

 b.      This gives you a pretty virgin install of the Operating System

 2.       Start Server Manager

 3.       Configure this server

 4.       Add the web server role

 5.       Add ASP.Net4.5 (and 3.5 if you want it)

 a.       the .Net 4.5 feature is already installed but you need to open it up and add ASP.Net 4.5 which is not there at the start.

 6.       In Web Server Role – Role Services; add Basic Authentication

 7.       Installing that lot takes five minutes or so

 8.       Return to server manager (you may be able to do this at the start but I ended up taking a second bite at it) | configure this server

 a.       Drill down to Web Server and on to Application Development

 b.      Add .Net Extensibility 4.5 (and 3.5 if you want it)

 c.       Add ASP.Net 4.5 (and 3.5 if you want it)

 9.       Installing them takes another few minutes.

 10.   Download DNN to the machine – the enhanced security stuff in IE is a is a pain.  Either tolerate it or turn it off like this

 a.        Server Manager | Local Server | Properties | IE Enhanced Security, click the On link and turn it off!

 b.      Close & Reopen IE to make it real.

 11.   Create a folder for your site and expand the DNN download into it

 12.   In IIS Manager create a Site/VirtualDirectory for your site and point it to the web site folder

 13.   Set the site to use the .Net 4.5 app pool.

 14.   Start SQL Server Management Studio

 15.   Add a Login for IIS APPPOOL\.NET v4.5 – you *have* to TYPE this.  You will NOT find it in the Search box

 16.   While you are at it, give that account Full Control over the folder your site is going into.

 17.   Create a Database for the site to use (Standard DNN process - outside scope of this guide)

 a.       allow your new login access to it

 b.      give the new login datareader, datawriter, dbowner rights

 18.   Modify the site web config to point at your database (Standard DNN process – outside this guide)

 19.   Allow Port80 traffic to your instance – this is done by changing the AWS security rules for your instance.  You CANT change the instance to use different rules so you have to change the rules it is using.

 20.   Launch IE and browse to your site to install DNN in the traditional way.

 a.       I cannot say with certainty that it does not work, but I have NEVER managed to make it work when installing from the browser on the instance.  It only worked for me when I browsed to the site from my remote (to the instance) laptop

That's it.  The site came up.