It's going to be hard to get a really good new bike for $400. I suggest you look for a good used bike. Like cars, bikes depreciate fast, and it's not that hard to get a bike that's $1200 new for $400 used, even one that's only a few years old. I have a ridiculously expensive bike now, but when I first started commuting, I walked into a used bike store and bought an old hard-tail mountain bike with road tires for $75. It wasn't the coolest bike ever, but the frame and components were vastly superior to anything you'll find at Walmart, and at a fraction of the cost. If you don't have a good used bike shop in your area, look at Craigslist or go to estate sales. Estate sales are sometimes a good idea, because sometimes the people selling just want to get rid of stuff. A friend of mine bought a 1970's Peugeot in mint condition (except for the tires) for $20.