This is a picture of my BeagleBone Black revC.
I included a nickel & a sharpie for scale.
There's probably ~$100 of Adafruit gear there including the BBB itself, miniHDMI-HDMI adapter cable, the miniUSB-USB cable, the case, the USB flash programming cable, the microSD & SD card adapter and the 5v2A DC power supply.
But another way to look at this is to round it up to $60. I will do that because if you were to get 10 of these & connect a network switch, that would probably be about $600.
Now let's assume that we have 10 in a row all connected up. Now let's add 9 more rows. We are in about $6,000 now and we have network backbone and power distribution hardware in place.
Now, mount that in a rack cabinet as a tray....and build 9 more such trays. We will need more power management, cable routing guides, and further network switching.
But now we are looking at a fully populated rack cabinet in a data center that contains 1,000 core processors & ~4Tb of flash RAM at a price of ~US$60,000.
Mind you - there are serious problems with this plan:
1. You currently can't buy >1 BBBrevC at a time due to supply constraints
2. BBBrevC has 100BaseT networking
3. All of the breakout headers and microHDMI ports will go unused
4. 4Gb flash RAM per unit - hard limit
5. There are no standard racks for any of this, so they will have to be custom fabricated.
6. Power distribution to 1,000 components will be a Challenge.
7. Will only run applications that can compile on ARM processors
However, there are benefits also:
1. Zero Noise - with no moving parts the entire enclosure is silent.
2. Less power consumption - 5v ~200mA each
3. Less heat generated - with little power consumed, not much to convert to heat. On board LED's can be disabled to further reduce consumption/heat generated.
4. Very low component cost - a unit actually fails? Throw it away & replace it!
5. Open Source Software - zero licensing costs
6. Open Source Hardware - when you can no longer buy them - you can send out & have them fabricated for you
When you look at what Google is doing in their own data centers now, this makes more & more sense.