Those prices are not bad.
Yeah. Tough call as I like the compactness of the Mini but I could use the horsepower of the graphics cards in the Pro for some of my photography work. It would be a no brainer if the photography work was more than just an expensive hobby. If you think about it, the computer does a lot more per dollar than does the constantly-refreshed camera.
That said, I haven't upgraded cameras since my Canon 10D and am typing this on my Early 2009 iMac. I'm such a tightwad! My iPhone 5S has more pixels than does my DSLR!