@4wd - Nice build! w00t!
I was going to spec one as an example, but you beat me to it - along with the price point I came up with. (My configuration came in at $138!)
- If you do build something like this, get over the natural tendency to try to cram everything into the smallest enclosure possible. Especially if it's a server that's going to be tucked out of sight behind a desk somewhere.
A decent quality mid-tower gives you the best bang for the buck, along with more airspace around your hot components. Recycling is also an option. Take the savings and invest in a better quality power supply if you have extra cash left over.
Small enclosures build up a lot of heat once you put a CPU and some hard drives in them. They're generally harder to work with, and cost a lot more to purchase.
Most of the power supplies that ship with small box enclosures also lack the capacity needed for multiple hard drives. So if you're planning to install more than one HD, start thinking outside the 'little' box.
Be sure to tally up the power requirements of each component in your build. Then do the math to get a correctly sized PS. You'll also want to factor in some additional capacity since your server will probably be left on 24/7. In situations like that, you never want to run your PS at near-100% load. Giving yourself an additional 20-30% will improve stability, increase operational life, and reduce generated heat. If the power supply has a variable speed fan, those lower temperatures will also result in quieter operation.
Another alternative to building from scratch is to look into some of the remarkably inexpensive "bare-bones" computer kits. Do a Google search on barebones computer
to get and idea of what's available.