Goodwill stores and Salvation Army stores have good bikes very cheap. Craig's list also has some good bikes. Take a friend who knows a lot about bikes with you when you are ready to buy a bike. If you will have only ONE bike, consider a mountain bike. A "mid-price" mountain bike (often sold used for $50 or $100) is tougher and more dependable than ANY road bike at any price. With slick tires, a mountain bike is great for five mile rides around town. If you begin riding 20 or 30 miles a day, you might prefer a road bike.