In your budget range, you are probably better off looking for a good used bicycle. What city are you in or near? Craigslist and local classifieds are a good start, but it helps to know a bit about quality versus junk.

By all means, I'd say you are better with a $250 1980's or 90's bike than you'd be with a brand new Wal-mart bike.

The main option for new bikes in your budget is sight unseen mail order (such as bikesdirect). As it has been mentioned, you would need to assemble this yourself (easy if you have basic mechanical skills) or budget time and money for a shop to do it ($75 or more).
Here are some samples of offerings from BD:

This one http://bikesdirect.com/products/mercier/kilott_wt5.htm is slightly out of your stated range but would be a solid bike.

This one is closer to your budget, and might offer the needed blend of comfort, style and efficiency: http://www.bikesdirect.com/products/...fe_latte_x.htm

If even more comfort is your desire, this one http://www.bikesdirect.com/products/...e_express8.htm has an 8 speed internal hub and a more upright "cafe" style.