Materials
The old metal lunch box that was a staple of school cafeterias from the 1930s to the 1970s became a collector's item once replaced by the plastic lunch boxes during the 1980s. Vinyl is also considered collectible due to the fact the material did not lend to a long life; finding one in good condition is rare.
Memories
Cartoons, television shows and movies all made their mark on lunchboxes over the years, proudly displaying a child's devotion for a favorite hero or pop culture character. Apparently you can put a price on nostalgia, because a Superman lunchbox from 1954 fetched a whopping $11,500 at auction in 2003.
Condition
Naturally, the better condition the more valuable the lunchbox. Other valuable physical characteristics include any date that might be stamped into the box. A matching thermos bottle in good condition increases the value of the lunchbox.