Well, the way I'm looking at it, if I find a lightly used late (11-12) MacPro on Craigs or somewhere (Craig's allows me to insist on running it through some paces before purchase), I'm confident of at least sub 2000 dollars, to maybe even a thousand. I'm lucky that I live in the NY Metro, a bit of a trek to Manhattan, but still able to travel into one of, if not the biggest graphics professional markets in the country. Throw in the geeky gamers and music "producers", and you get a lot of towers changing hands. Anyway, I'm pretty sure that computer will be functional with plenty of Ram installed for, at least, five years. The death knell would be an introduction of an OS that can't be run on that computer. So, fine. Buy the latest thing then, or do the same as the last time, and nail a used machine at a 50% discount.
I've worked with the best Macs of their time for about 25 years (at my employer's expense), and one thing I can say is that they don't break, and I have been on machines that are worked 2-3 shifts a workday. Rock solid. And now we have reached an interesting point in PC development for photography, when maybe where we are, is good enough, and the industry has moved on to cater to the video geeks. You know, how much faster can some things get? Sure, instantaneous, but we're pretty close.
My last employer switched from the old MacPro tower to the trashcan a year and a half ago, justifying the cost by moving into 3D. That went FUBAR, but, I wasn't impressed by the difference of speed in Photoshop functions. It was a lot smaller, and looked really cool, and totally quiet. But, 2-3000 dollars for a little cool and quiet? Eh.
