 According to Sinclair himself , the £ 69 @.@ 95 price was chosen after applying the " experience curve " developed by the Boston Consulting Group . Sinclair 's prior experience in the calculator market had highlighted the fact that a product will be more profitable selling at ( for instance ) twice the manufactured cost than at three times . He could have launched the ZX81 at a higher price , marketing it in a more traditional way as a premium product , but chose not to . In effect , he used the lower price to establish an unassailable lead before the competition moved in . 
