The average price of one of these devices is $145, calculated roughly. The cheapest devices also need peripherals that further increase the cost.
For roughly the same cost you can get a used laptop off ebay which can beat all of them in terms of system resources and most of them in terms of portability. It will however be a bit more expensive to run in terms of electricity.
Just putting my 2c in, after doing some research on the topic in hope of setting up a low-cost, low-maintenance server.
For roughly the same cost you can get a used laptop off ebay
I'm going to assume that we're talking about building an embedded device, controller, standalone appliance that interacts with the real world -- this is the intended market for most of the devices in the original article.
If you need to set up just one server or controller, a used laptop off eBay is a sensible way to go.
But if you're going to need a whole bunch of them, doing it that way will cause a ton of development grief. I've been there.
Unless you can be assured of a steady supply of exactly the same used laptop or whatever used device you're looking for, each variation that you buy will have some difference in firmware, BIOS, peripheral support, interface connectors, or whatever that will cause you to spend massive time adapting your software or hardware to it.
The money you save by buying cheap used systems will be nullified by the extra development you have to do for each variation.
I agree with what you say. I also noticed that if you're able to crystallize the reasons you want a linux computer for, then you can make a decision between the screen and screen-less ones. For instance, if you need a low powered media player directly connected to the HDMI port on your TV, then you'd obviously go for a screenless computer. In that particular category, the Allwinner MK802 surprisingly strikes me as a valid and very powerful competitor to the others. It needs an μSD card and one of those cheap bluetooth keyboards, along with a bluetooth adapter. It'd be pushing almost $100 bucks at that point.
In which case, you look hard again and figure out are you really trying to buy a media player, since if yes, you could get a Roku or something for much cheaper, or do you want an el-cheapo Android machine. If it's the latter, you'd better wait for the Ouya assuming it's going to be a success because at that price it's literally a steal. If you can't wait for the Ouya and still want one of these toys, I think the Allwinner even beats the Raspberry Pi, which I was so fanatical about initially, but after seeing so many other options I'm not sure if I want one anymore. Speaking of the RPi, I think the killer feature is that it has GPIO, so if you're trying to hack up some cool car or washing machine doohickeys then that might be up your alley.
Other than these two for screenless, I don't really see any value for money propositions. The screened variants fall even harder because they need to accommodate the cost of a screen and a keyboard, which results in an XScale processor. I honestly do not know what uses I could put these screened computers to.
For roughly the same cost you can get a used laptop off ebay which can beat all of them in terms of system resources and most of them in terms of portability. It will however be a bit more expensive to run in terms of electricity.
Just putting my 2c in, after doing some research on the topic in hope of setting up a low-cost, low-maintenance server.