$599 for a mini would be stopping me for me one. Since I'm not getting paid to do mobile development $599 is money that could get me a holiday or a used car, I'm not trying to make angry birds here; just a few tools to make my life easier. Besides it seems silly to spend all that money on a low spec Mac when I already have a perfectly serviceable workstation that I have invested in.
Even if it cost them a fair amount of money to port it all over, they're Apple so they have the money in the bank. Plus I can imagine the ROI would be fairly significant when you consider how many more people could get into casual iOS development and then potentially make it into a full time thing.