Here is an interesting new sub $100 ARM board. I may have to order one to play with! It has many good features, the one I like is that it can run the full Ubuntu desktop.
From their Web site:
The features of the cubieboard:
1G ARM cortex-A8 processor, NEON, VFPv3, 256KB L2 cache
Mali400, OpenGL ES GPU
HDMI 1080p Output
4GB Nand Flash
2 USB Host, 1 MMC slot, 1 SATA, 1 ir
96 extend pin including i2c, spi, lvds, sensors, ..
Running Android, Ubuntu and other Linux distributions
There is a nice simple case for the board. Look here http://cubieboard.org/2012/09/10/a-simple-case/