Many things determine the price of an antique or collectible. Prints are especially difficult to judge if you're a beginner. You must learn to recognize a print, etching, engraving, lithograph, chromolithograph, photograph, and modern copies of oil paintings, watercolors, pastels, hand-colored prints or enhanced oil paintings. Each one is in a different price range.  See Kovels' online price guide for prices of all of these types of pictures.