Indeed, $100 will get you a used/downmarket bike that will move you around just fine. And if you've got a bit more money and want something sturdier, you can get a brand-new model from a respected manufacturer for $500. I paid an extra $80 or so for a strong cargo rack and deep, low-slung, waterproof saddlebags that can carry more than a week of groceries for one person. So there really is a range of options for every income.