When the Raspberry Pi project was unveiled more than a year ago, two models were promised: one costing $25 and a more powerful one for $35. Ultimately, only the $35 device went on sale, to extreme popularity, with possibly a million sold.

But for those of you who felt $35 was just too expensive for a computer, that $25 "Model A" is finally available. It's now on sale in Europe, and the company will "lift this restriction very soon so the rest of the world can order too," Raspberry Pi spokeswoman Liz Upton wrote today.

Model A has one USB port instead of two. It also lacks an Ethernet port and comes with 256MB RAM, as opposed to the 512MB of RAM the latest version of Model B ships with. Without Ethernet, users needing Internet access have to use the USB port for a Wi-Fi adapter. Thus, if you need Internet and an extra USB port for a keyboard or other peripheral, a USB splitter would be necessary (which may require a powered USB hub).

Model A does have key advantages in power consumption, however, meaning the lower price alone isn't its only draw. Robotics projects might be a good fit for the cheaper model.

"The Model A is a stripped-down version of the Model B Raspberry Pi, with no Ethernet, one USB port, and 256MB RAM," Upton wrote. "Stripping down the Model A means it has two important differences from the Model B: we can make it $10 cheaper, at $25; and it consumes roughly a third of the power of the Model B, which is of key importance to those of you wanting to run projects from a battery or solar power: robots, sensor platforms in remote locations, Wi-Fi repeaters attached to the local bus stop, and so forth. We’re working on software to get the power consumption even lower. And we’ve seen how well XBMC works on the early 256MB Model Bs we sold last year; it’ll work just as well if you want to make a $25 media centre out of your Model A."

It doesn't sound like there will be a huge delay before Model A is available in the US and other non-European countries. Upton wrote that "paperwork" is the main reason for the holdup.

Upton concluded by saying, "We are very, very pleased to finally be able to offer you a computer for $25. It’s what we said we’d do all along, and we can’t wait to see what you do with it."