If you're that basic though, why build it on its own board? For 4 components, just put the bare components on the perfboard or breadboard (and then you're under $5). Also, the stamp seems to lack proper crystal which is important if you want the Arduino timings to work precisely.
Fundamental Logic is a great store, I've had very good experiences when purchasing from them, and for breadboard work, I strongly recommend their iDuino board over this stamp -- it's a few dollars more and gives you a full blown arduino that sits on a breadboard. And pick up a few extra MCU's for finished projected.