i can't believe that there is no more support for parts any mor

i can understand that software support need hardware ability. but spare parts? what on earth . i have 2 desk tops need power supply 2006 and 2008 and its look like apple stopped the spare parts for both of them . ok some of will wonder saing its tool old mac . my answer to them why we buy apple stuf ? because its last longer than the others. but what defrint its make if there is no more parts to last that long