Question: I am a sole developer currently backing up my source code to .zip files on an external drive. Is it worthwhile for me to start looking at code repositories? What's the simplest, cheapest option for me? (ie. There is no need for lots of fancy features as the repository is just as a backup and not for sharing with a team).

... Forgot to mention. I use Visual Studio 2010 only.

Answer: 
SVN would be perfect for you!!

I use Visual Studio 2010 as well, and there's a great open source plugin for working with SVN - [AnkhSVN](http://ankhsvn.open.collab.net/)
Since you're working with VS2010 I suggest you start working with [**TFS2010 Basic**](https://devblogs.microsoft.com/bharry/tfs-2010-for-sourcesafe-users/).