I'm a bit late reading this, but thought I'd mention - you could build your own Arduino (at least the Uno type), thus using whatever spec components you want. I can build a clone for about $3.50 in parts from Mouser. The most basic form is just the AVR chip, a crystal/ceramic oscillator (and you don't even need that if the internal LC oscillator will work for you) and a couple resistors and capacitors.
A few lines wired to a header let me plug in a USB/serial converter (called FTDI Friend) to do programming that would normally be done with the Arduino's USB interface.
It also means you can select a better voltage regulator - the one on the original Arduino board is pushed pretty hard, especially if you use much more than 9V input.
Also you can then custom-configure the PCB to any shape you want/need.
One of the first home-brew boards I made is an AVR programmer. It has a ZIF socket, I buy unprogrammed AVRs, drop them in, press a button and it zaps them with the Arduino boot-loader (if that's the right term) so I can then use the chip with the Arduino IDE. Several places also sell pre-loaded AVRs for a couple bucks more so you can skip that step.
A good schematic to get an idea what a more stripped-down version looks like is:
http://learn.adafruit.com/system/assets/assets/000/010/223/original/boarduinosch.pngThis is the "Boarduino" from Adafruit. I use them for prototyping since they plug into the breadboard nicely, and this schematic comes in handy for remembering what I need when building my own.