Cheap replacement watch batteries are good and do work, but they do not keep a charge as long as many name-brand batteries. However, watches that have many features or require a high voltage charge do not function as well with a cheap replacement battery.
Factors that affect the price point of watch batteries are brand, type of battery and chemical makeup. The alkaline battery is the most inexpensive type of watch battery, and it keeps low-tech watches operating for months. Lithium ion and silver oxide batteries last much longer and are ideal for watches that offer more features such as lights, alarms and digital displays. These batteries are more expensive, but the costs can be nearly the same over time as using the cheaper batteries.