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: 
Get yourself subversion, mercurial, git, cvs, anything is a vast improvement over zip files. You can generally get free plugins for VS as well although they aren't necessary.
Since you're working with VS2010 I suggest you start working with [**TFS2010 Basic**](https://devblogs.microsoft.com/bharry/tfs-2010-for-sourcesafe-users/).