This scheme shows how to make an Arduino Compatible Board with a 1000Pads-Mini Basic Board.
Just connect a USB to Serial converter or a 1000Pads-Mini USB2Serial Board and you have a cheap, compact and fully functional Arduino Compatible Board.
Note: The ATMega 328 needs the Arduino Bootloader. You can buy an ATMega 328 with the Arduino Bootloader pre-programmed or an empty Atmega 328 (or 168) and then burn it with the Bootloader, in this case you need a Programmer.