[Rychard]

> I suspect the cost of a raspberry pi isn't much higher than a new battery.

Don't forget that you'd have to factor in the cost of a display, input devices, and storage if you go the Raspberry Pi route. And if you wanted the Pi to be portable (as your alternative suggestion seemingly implies) you'd have to buy a battery for it as well.

On the other hand, if you don't need the Pi to be portable, you might as well just leave the laptop plugged in and use it instead, as you wouldn't have to spend any money at all to achieve the same end-result as purchasing the Pi.

In fact, I would wager that putting together a Raspberry Pi solution comparable to a cheap laptop would be difficult for any given price point; if the laptop is just "old" and not "broken", I would further argue that it provides a much better user-experience.

I don't intend for this to be a criticism of the Raspberry Pi. In the article they're using old CRT televisions which negate the cost of a display, and keyboards and mice are readily available from a number of places for free (or close to it). For their use-case, it seems to be quite an effective solution.