Sir Clive Sinclair in the UK should be credited with inventing the mass market computer. Commodore 64 launch price on the UK was £299 whereas the ZX Spectrum was £129 and it's predecessor the ZX81 sold for £70. Clive wanted to set a price point so that ordinary people could buy one. He started with the price and built a machine to meet that price. This made it accessible to most people as the Commodore 64 would have been outside the budget of most households.
