To evaluate the value of an antique camera, find out everything you can about the camera, and look it up in a price guide. The guide may indicate several values for the same camera in different conditions. One good price guide is "McKeown's Price Guide to Antique & Classic Cameras." You can also look up the value of the particular camera on eBay using the advanced search option.
To get the most accurate estimate of the camera's value, find out its make, model, serial number, condition and film type, and determine if the camera works. If you don't have a lot of experience dealing with antique cameras, take the camera to a local camera shop or a professional photographer who has experience with antique cameras to examine the camera's condition and functionality.
As of 2015, to perform an advanced search on eBay, go to the home page, and click Advanced next to the search function. Looking at the prices of items that have already sold gives a more accurate representation of the camera's value, so select the Completed Listings option, and type in the camera's make and model. Try to look at the prices of cameras that are in a condition similar to your camera's.