The DIY approach is one of our favourite options when it comes to NAS setups. This tiny, super-portable NAS in a box would be a good weekend project to try. While you'll need to be comfortable with a soldering iron to make this DIY NAS work, it's smaller, more portable and just as functional as larger off-the-shelf or DIY options.
David posted the walkthrough on his own site. David snagged the server itself for a little over $US30, repurposed a pair of old laptop hard drives, some USB-to-IDE cables and a USB hub he snagged off eBay, and an old tin box he repurposed for the project.
He started with a Linux distro made for the server he purchased, but he eventually shifted to OpenWRT and built his own image with the specific tools he wanted for his NAS. It's definitely an advanced project and will take some time, especially for novices, but if you're a DIY fiend, this is a project for you.