As a rule, surplus stores are mildly disreputable. They take the leftovers or discontinued items, which they purchase at a reduced price, or get for free, and resell them. Many dollar stores operate this way. American Science and Surplus is different.
Their mission is narrow - they only accept surplus items that are - in some way - related to science. As their manifesto says, "we are fascinated by discovery and invention" and their ever-changing inventory reflects that.
Their story began in about 1937, when Al Luebber stumbled across lenses that a near-by glass factory were throwing away. Al and his wife cleaned the lenses and sold them through a mail-order ad in Popular Science. Fueled by military surplus after World War II, the Luebbers opened a real shop and called it American Lens and Photo. Al's son, Jerry, grew the business through the early 80s. After his unexpected death, the shop changed hands a couple of times and now is owned by Philip Cable, "a life-long science geek."
Chicago middle-school science teachers love American Science and Surplus. Though the inventory changes, the gems are always there. Kits - from boats to hearts - can be found for your favorite curious 12-year old. They usually have some sort of binoculars, telescope or microscope available. Looking for a DC analog dial ammeter? A Boy-Scout-in-a-bottle? An induction motor?
American Science and Surplus reveals all the information they know about the origin and manufacture of their goods, even if all they know is that it was "made sometime in the past in Chicago." They accept all returns - as if you'd need to return anything!
(This is the original location of the store, however one in Milwaukee, Wisconsin, is also listed in the Atlas Obscura. There is a third store in Geneva, Illinois.)