This is what I'm planning on doing.

[Silicate Wielder]

Hey guys, so I just turned 15 (yay!!) meaning if I'm up to getting a job this year I'll be saving up to build my own personal small-scale server.

I'm going for something small that costs around $1000 to $1200 made from a mix of new and used parts.

It has to be portable enough to take with me if I move (I'll use any empty space I can to store my junk if I have to), but capable of running a private minecraft server, a personal media streaming center (We go through too many DVDs so I make backups, however its a pain to manually transfer files as needed), and then some for personal use.

What do you guys think, and any tips or suggestions?

[TheMatrix]

The problem with servers is that most were not designed with energy savings in mind. So your parents may not be thrilled with their energy bill.
Nevertheless, I'm sure you could make something. My PC, if you haven't seen my other posts, is a server that I put in a desktop case.

I bought it here (http://www.halted.com/commerce/catalog/product.jsp?product_id=22529)(although I saved 50 cents and a whole lot of shipping costs by going to the store itself), but be aware it's only a motherboard, Pentium4 HT processor, 240W PSU, and extremely loud blower fan. You have to buy everything else, which for me, was:

Memory - DDR1. It's expensive as fuck. I have 3GB in mine right now.
Graphics card - nVidia GeForce FX 5500. It only has PCI(not PCI-E), which severely limits one's options. Maybe not applicable for a server. The stock one is an ATI Rage XL with 8MB VRAM
hard drives. It has 2 IDE and 2 SATA buses. SATA supports RAID, should you want it.
WiFi card. You mentioned portability, but it does have 2x 1 Gbps ethernet connections. I need it because there's no ethernet cables in my room, yet. It's an Atheros something-or-other.
DVD/CD-ROM drive(s). It does not support booting from DVD or USB flash, only CD, floppy, ZIP disk(hah), USB-CDROM, USB-ZIP, PXE, and something else. Make installation media accordingly.
A CPU fan that fits. I don't remember the socket type, but I could find it for you if needed.

I think a 1U pizza box is very portable, and you can even pick it up by the handles on the front(wouldn't recommend it, though).

It's an interesting idea, but wouldn't an extra or external hard drive work just as well?

[Hypers]

Since you're building a minecraft server, I suggest you get tons of fast RAM and a fast Internet service.

[gothicsanctum]

Your ISP might not be happy with the amount of bandwidth required for a MC server.