Now I do that to almost all my projects.
It costs around 7-10$ for the parts you ned to make the Atmega328 work.
So it´s really worth it to do if you are content with your projekt that involving the Arduino.
I ordered the ATmega328 chip with the 16Mhz crystal and two 22pF capacitors.
Then I bought a 5 voltage regulator,10nF and a 22uF capacitor. Then some resistors and transistors for the led cube.
As you can se it´s a 3x3x3 led cube so you need 27 leds and 9 resistors and 3 NPN transistors.
I hope this gave me some inspiration.
I would appreciate if you comment and say what you thought.