At first sight it seems a fair margin --- clearly not $130 for every iPod Shuffle, but $130 for every Mac Pro is far too little to be competitive.
But there's so many apple-device-less sales: applecare extended warranties (linked to a device, but clearly a separate service), applestores selling all kinds of trinkets (USB cables, docks, Epson printers, whatever), iTunes and appstore, boxed software, ...
So your rough per-device profit is a bit meaningless, all in all. Show me an overpriced device, seems the simplest approach.
[When the MacMini was disassembled and costs summed up, a cry of "overpriced! outrageously so!" followed --- but all competitors that tried made either a more expensive or an inferiorly specced product (and several cleverly did both at once), so not much more was heard from that. Same with the first iPods --- decent-brand competitors weren't any substantially cheaper... Only the chunky no-name flash players are cheaper per GB. And don't mention the Zune. Quality competitors do have to go for features, alternative design, and audio quality never price.]