Like my friend Darana said this is Nerds R Us. Somebody compiled hard drive costs from Newegg and plotted a graph of GB/dollar across various drive sizes and came up with a basic point graph here. Looks like right now the sweet spot is 500GB drives where you can get just over 5GB for each of your hard-earned dollars (~$100). He did the same thing for flash memory cards but there isn’t an obvious sweet spot on the graph. The HDD plot is actually a slightly-skewed bell curve though.
His picture on the main page is a bit creepy but if he’s programming in Python, C and PHP and he is “currently 14.6906376277 years old” then he’s got a great future ahead of him. He’s even working on the PCB for a quad-rotor UAV.