I work as a bike mechanic and build up all my own bikes to suit my personal preferences.

I personally like drop bars and all my regular commuters have them... all are randonneur type bars which have a slightly different shape than what you would see on a full on road bike as they are better suited for long distance riding.

If you have the skills and tools building up your own bike can be really satisfying although it can take longer than buying off the rack... and once you get that bike you will probably start to experience some upgraditus and change a few things. If you were to come across a nice older touring bike they make excellent commuters as they have accommodations for racks and fenders and can move out at some good speed.

I have a 1982 Trek 610 touring bike that I have used for commuting and have also taken it on some pretty fast road rides with friends who were a little astonished at how fast a touring bike can be and is certainly far more comfortable.

Also... the most expensive commuter I have is that Trek as it was picked up very cheaply and over time I replaced the parts I didn't like, the build up cost has to be sub $400.00 and the bike has been bombproof.