Stuff like that makes the economist's heart rate go faster - great work! Apple Matters has an interesting piece about Mac resale values which shows the actual fair value depreciation on Mac laptops, based on ebay prices. For a three years old laptop, you still get to recoup some 40% of its purchase price. This is exceptional, seeing how our tax depreciation allows for up to 80% in the first year!
This should be proof enough that the old stereotype that Macs are expensive couldn't be further from the truth. And I am not talking total cost of ownership (which, if done right, would actually include resale value unlike in this example), although that would be the proper metric, but only cash out/in when you buy and sell your machine. Given that Macs cost about the same as your garden variety PC for comparable configurations nowadays, it's safe to say that Macs are cheaper.