Timex Sinclair 1000
In 1981, Sinclair released a computer at a price that is still crazy 30 years later: $99.95. The Timex Sinclair 1000, also known as the ZX81, was small, ran on BASIC, and offered a mere 2KB of RAM to go with its 3.25 MHz processor. Even by 1981's standards, it was slow -- but it also cost a mere 100 bucks, making it an attractive entry point for aspiring hobbyists who couldn't spend a thousand dollars on a PC.
Thanks to its price, the Timex Sinclair 1000 sold over 600,000 units in the United States [source: Old Computers]. The Timex Sinclair 1000's performance was infamously slow--because the computer contained a mere four chips, it relied on its CPU to handle all of its processing and refresh whatever external display it was attached to. Switching to "FAST" mode would speed up calculations but cause a terrible screen refresh rate. Thankfully, the computer supported tons of expansions, like floppy drives and RAM add-ons, that greatly improved its functionality.