It all started with a theory about the Internet and a broken laser pointer. EBay launched Labor Day weekend 1995 under 28-year-old founder Pierre Omidyar’s belief in the power of an online community.

As any stingy electronics tinkerer can tell you, eBay is a great place for getting components in bulk and on the cheap. They may not be high quality, and they may not be 100 percent reliable, but for ...