gerv 

But... hate to remind you of this... the cost of a bike goes beyond the initial price. For example, a good LBS will do adjustments. Give you advice. Will have tubes if you need some in a hurry. If you blow out a bottom bracket, they can fix it pretty quick. Then, there's the idea of supporting your local community.

I mean, if you are up to doing all those repairs, I would consider going with BD. But if you are going to need support...

As a commuter, you must realize that having a bike is a tremendous value, even if your initial costs are a bit more. If you figure out your cost per month, it's often worth spending a little extra money to have a little extra convenience.