Loved this guy professor Simon Cox - what a bloody boffin - amazing technical knowledge, decided to build a supercomputer using Rasberry Pi's and lego for the casement, marvellous. surely cost a lot less than $1000  its 32 nodes so probably more like $2500..
Heres how if you fancy making one yourself
from another build i saw, its performance is around 10 gigaflops(..?) the first cray supercomputer was less than 2 in 1985