You can pretty much get anything you want for $300. I have no preference between Sugino 75s, Dura Ace, and SRAM Omniums.
$300 on cranks for a 6 mile commute is pretty overkill, but then again I have Omniums on my daily. What's the rest of your setup? Why don't you take some extra money and put it towards some nicer wheels/saddle/bars or something?