Pez started life as a small breath mint for adults, originally produced in Austria ('pez' is a sort of contraction for pfefferminz, the German term for peppermint. The candy was marketed in a slim, stylish dispenser that allowed individual candies to be accessed with a quick flick of the wrist. The dispenser originally resembled nothing so much as cigarette lighters, and indeed the mint was marketed to smokers both as a breath mint and as a substitute for cigarettes. In the early 1950's, the candy was first marketed to the United States, but while adults seemed to like them, kids didn't pay much attention; fruit flavors were introduced to garner some interest. Then some genius got the idea to decorate the dispensers as amusing little characters - and a phenomenon was born.
Somewhere between 300 and 400 differently-headed Pez dispensers have been manufactured and sold since then - and, as with most amusing, creative items, a cult of collectors has arisen dedicated to hunting down and hoarding every single head, color variation, and style of dispenser in existence. Some popular vintage and modern characters to have been modeled include Santa Claus, astronauts, various Star Wars people, cartoons, animals, clowns - even the guys from Orange County Chopper.
Naturally, as with all collectibles, there are rare and valuable items that tantalize the hardcore collectors. Original promotional and display items - the older the better - are heavily in demand because of their scarcity. But the real collectors salivate over the rarest dispensers: the one featuring a large eyeball resting in a hand, with a psychedelically-painted stem; the 'make-a-face' dispenser, on which kids could interchange facial features like a miniature Mr. Potato Head (but which was quickly withdrawn over choking-hazard concerns).
Possibly the rarest of all, however, is the feared and dreaded '1982 World's Fair Astronaut With Green Stem.' It is a rare variation (one of a kind?) of a more common astronaut-headed dispenser, probably a prototype to be issued at the Knoxville, Tennessee-based World's Fair that year, but never released. It sold on eBay in August of 2006 for over $32,000.
And if that doesn't get you out to the garage sales this summer, nothing will.