 By the late 1970s , American companies were producing simple home computer kits such as the MITS Altair and IMSAI 8080 . This aroused interest among electronics hobbyists in the UK but relatively high prices and lower disposable income reduced the appeal of the American products . New Scientist stated in 1977 that " the price of an American kit in dollars rapidly translates into the same figure in pounds sterling by the time it has reached the shores of Britain " . Off @-@ the @-@ shelf personal computers were also available for the high end of the market but were extremely expensive ; Olivetti 's offering cost £ 2 @,@ 000 , and the Commodore PET , launched in 1979 , sold for £ 700 . There was nothing for the hobbyist at the low end of the market . Sinclair realised that this provided a useful commercial opportunity . 
