Just posted (well, just noticed anyway) at dipmicro:
"Chip only! ATMEGA328P-PU with Arduino UNO Optiboot bootloader (external clock 16MHz). This IC allows you to replace faulty chip on your UNO board or use Arduino sketch in your project without Arduino board. To use without UNO board, minimal external parts are 16MHz crystal and two 18pF capacitors. Chip comes pre-programmed with bootloader plus blinky sketch, labeled and leads straightened to fit easily into IC socket. "
$4.55 USD
And these guys have very inexpensive shipping costs too.