In 1978, the Cray-1 supercomputer cost $7 million, weighed 10,500 pounds and had a 115 kilowatt power supply. It was, by far, the fastest computer in the world.
The Raspberry Pi costs around $70 (CPU board, case, power supply, SD Card), weighs a few ounces, uses a five watt power supply and is more than 4.5 times faster than the Cray 1.