Well I have a 2006, I replaced mine with new aftermarket ones, nobody knows any better, but I often hear people assuming my car is a much newer model than it actually is, probably because of the new headlights.
Go to ebay.com look for "chevy cobalt headlamp pair" you can get them for less than $100, and simply replace your old ones with those. I get lots of compliments about my headlights, well worth it.
If your looking for custom headlights, like halos and projectors, you can also check ebay too.
Old Car: Chevy Cobalt 2006 LS Sedan base (Automatic)
New Car: Chevy Impala 2011 LT Fully Loaded (Automatic)