What kind of bike are you looking to get? If you don't want expensive, don't go the roadbike route. They start at about $500ish and go up quickly from there, and you wouldn't be able to find them at Target, anyway. They are the best for racing and fitness.
Cruisers are just that--for cruising. Generally, they are heavier, won't go as fast, have a cushy seat, and long, curvy handlebars.
Hyrbids are something in between. They are not as pricey as roadbikes (generally) and they are lighter than cruisers.
You also have mountain bikes, which, riding in the city, you probably don't want.
I would probably go with a hybrid if I were you. I strongly suggest going to a bike store and looking around, even if you don't buy. Talk to them about what you're looking for. Your best bet would be to buy a used bike from a bike shop. The bikes at chain stores like Target are really not quality bikes, have a lot more problems, and are put together by people who do not know bikes, not to mention you are supporting small, local businesses when you go through a bike shop. I got my hybrid used at a bike store for about $75. I spent about $400 for my new cruiser, and now, I'm dreaming about getting a road bike.
Hope this helps. I would avoid chain stores like the plague, though.
