I am looking through the pre-made bikes. Is there any suggestions on a bike that is $500 or less that will be good for daily commuting 10 miles round trip.
YES.
Here -
http://www.bikesdirect.com/products/trackbikes.htm
The downsides are that the stickers don't come off, the paint jobs aren't to everybody's taste, and they'll need a little assembly/truing.
On the plus side, the frames are the same as a number of "name brand" fixies since they're made in the same factories in Taiwan and just have different paint, they're equivalent in terms of build level to a lot of the $500-600 bikes, and they're pretty sturdy.