There are several ways to determine an antique camera's value, such as searching the camera's model number with a search engine and searching for price information on e-commerce websites. A search engine may bring up a link to a page that describes the camera model in question, including the monetary value.
Specialty websites, such as Manfredshmidt.com, sell antique cameras, and they may have a camera of the same model as yours listed for sale. The listed price provides an approximate value of your camera.
Another method is to visit eBay and search for your camera's model number with the search tool. Be aware, however, that the current bid amounts don't usually reflect the camera's value because the current bid is usually far lower than the final bid. Rather than looking at current bids, search listings with a "buy now" price. This amount indicates the full asking price, which provides a better representation of the camera's value.
Another tool that provides information about antique cameras and their value is a price guide entitled "McKeown's Price Guide to Antique and Classic Cameras." The guide contains over 1200 pages and it lists over 10,000 cameras, some of which are hard to find on the Internet. It costs over $100, but collectors often consider it a worthwhile investment.