Sometimes the free market produces products that fill a genuine need at a sensible price. But sometimes it produces stuff that’s just plain neat.

Today marks the sales launch of Sifteo Cubes, which were first unveiled back at January’s CES show. They are simply 1.5 inch cubes with an electronic display, wi-fi connection and three-dimensional motion-sensors.

So what can they do? Well, that seems limited only by the imagination of game designers. Some of them are simple: one randomly produces letters which you have to rearrange into words. Another takes the gameplay of card game Rummy and turns into a dining themed game, Smorgasbord. Blok 9 is a strategy board game (without the board.) And No Evil Monkeys is a 3D version of the old slide-the-tiles puzzle. Those who’ve played the games report that they are surprisingly compelling.

There are some major catches however. The cubes only work when your computer is switched on, and the audio from the games comes from the computer, so you need to be within earshot to play. Battery life is limited to three hours, so parents hoping to use the toys as a babysitter might be disappointed.

And then there’s the price: $149 for a starter pack with three cubes and $49 for each additional cube. All games should work with three cubes, with the additional ones bringing extra depth and complexity. All cubes are compatible, so friends can bring their own cubes to play, and games support up to six cubes.

Aside from two that are bundled with the cubes, games have to be bought individually, with pricing not yet made public. That’s likely to be a big limitation as I can’t see many people splashing out on the devices until they can be sure there’ll be plenty of games at a decent price.

However, the starter pack does include a Sifteo Creativity Kit that allows users to create and share their own games without needing to learn any code, which should make them much more appealing to parents looking for an “educational” toy for kids.