I feel like every one of these threads and posts all over the internet is missing one crucial part of the New Mac Pro.
THE SIZE!!!
The New Mac Pro is at least 5 times smaller, probably even more than that of the Ebay link in the original post. To get those specs in that size is unheard of. If you can find a suitable alternative to the mac pro, at that size factor, with similar or better specs for a smaller price, You would literally be a legend. But seeing as nobody but Apple offers anywhere near the specs of the new mac pro in that size, you'd be VERY hard pressed to find that.
It's not even hard to customize either. You can go ahead and buy 16GB of RAM from Apple when you buy the computer and upgrade it whenever you want to 32GB or even 64GB from the many third party sources who are already stocking RAM compatible with the New Mac Pro. It might take some time before third party manufacturers have mac pro compatible flash storage but I have no doubt it will come. ifixit.com gave it a pretty formidable upgradability and repairability score of 8 during its teardown on their website.
The New Mac Pro is not designed to be "The very best specs for a decent price". It is marketed to be a small, easy to transport workstation for those who have intensive computing needs but limited desk space. The New Mac Pro is literally the example of what apple is all about. Better, smaller, easier to use. Notice how all their laptops, every year become thinner and lighter while still increasing performance. Another thing to do is to find a similar spec'd laptop with the size and weight of an apple macbook. Bet you'd be searching for a while because it is pretty difficult to do.
Did Apple not recently release a new iPad called iPad Air. Do I need to give any more examples?
If you can find me a computer with the same specs, same size, and same weight, for the same or cheaper price, while not sacrificing performance to overheating, please feel free to show me and I will take back all I have said.
I hope this quashed any ideas that Mac is overpriced simply because of the specs. You buy Mac not simply for specs, you buy it because you know something others don't.