Hidden cameras can be purchased online from a variety of retailers specializing in surveillance equipment and spy gadgets. Some popular websites to buy hidden cameras include Amazon, eBay, Best Buy, Walmart, and SpyTech. These online stores offer a wide selection of hidden cameras in various shapes and sizes, including hidden cameras disguised as everyday objects like alarm clocks, pens, and USB chargers. Customers can choose from different features such as motion detection, night vision, and Wi-Fi connectivity. It is important to do thorough research and read reviews before purchasing a hidden camera to ensure quality and reliability.