Buying the cheapest computer in the world is now cheaper than buying your lunch.

The Raspberry Pi Zero is on sale for $5 US ($6.65 Cdn) from the U.K.-based Raspberry Pi Foundation. The educational charity's goal is to get children more interested in programming by giving them a cheap, simple computer so they can experiment.

"We really don't think we'll get any cheaper than this. We've gone from say, four lattes, to one latte. We're not going to go below the cost of one latte," said Eben Upton, founder of Rapsberry Pi in a video posted on Vimeo. "We really hope that's going to get the last few people in the door and involved in computer programming."

The Raspberry Pi Zero has a 1GHz ARM11 processor core that is 40 per cent faster than the one on the original Raspberry Pi and 512 megabytes of RAM. It runs Raspbian, a free operating system based on Linux and optimized for Raspberry Pi computers.

While the tiny computer, smaller than a credit card, has a variety of ports for plugging in crucial accessories like a screen, a mouse and a keyboard, it doesn't come with any of those items or the cables to plug them in. That means you would need to spend a little more than $5 to use it.

So far, Raspberry Pi Zero is available from a handful of U.K. and U.S.-based retailers.

The foundation says it has produced a few tens of thousands, with some coming free with its magazine, MagPi, which is available on newsstands in the U.K.

The foundation launched the first version of the Raspberry Pi in 2012 for $35 US and it sold out within weeks. Cheaper versions later became available for as little as $20.

The foundation's newer version that can run Windows 10 launched in February for $35.