It's really not very complicated at all mikeymike, the only relevant comparison for anyone thinking of buying a NG system *today*, are what options are available *today* (not a decade ago, not a decade into the future when/if OS4 finally supports the HW fully)! I'm talking about hardware availability, hardware price, hardware performance, hardware quality, what features the OS has, what Amiga Standards (like MUI, Poseidon, CGX, etc) the OS has, the performance of the OS, the level of Amiga compatibility in the OS, the stability of the OS, etc. Learning things like this, might help you make a well educated purchase decision, *not* having access to this kind of info may lead to people being fooled to buy a $3,000+ system while being of the wrong impression that it would be the only or the best alternative. Knowledge is good! 
The motherboard design may be new, but the core PA6T was created in 2005 to be ready for laptops in 2007, but got shelved after Apple went x86 and bought PA Semi for the competence and pulled the plug on the PPC things, so it's at least half a decade old technology, aimed for mobile/power saving applications, and all this clearly shows in benchmarks.
To begin with, a straight-forward question was asked, how much does the X1000 retail for. There wasn't any ambiguity to the question whatsoever. The poster didn't ask for help or advice. You decided that instead of answering that question in a one-line helpful response, you came up with your almost completely unhelpful response.
You're comparing a second-hand, approx. 10 year old system with a brand-new one. Yes, it's brand-new. No-one has used it before, it is being sold as-new, with a warranty, no question there. I would also expect a level of hardware and software support with the purchase, for the length of the warranty at least.
A PowerMac G4 is approximately ten years old. You can only get one second-hand, no guarantee, and I would expect pretty much any general-purpose computer of that age to be a bargain basement price because it is well past its sell-by date, there's no guarantee how long the hardware will last or what condition it is in now. The current version of Apple's intended OS for this product will not work on it, so by that metric (as well as software support for MacOS), the product is obsolete. I assume that it is technically possible to run AmigaOS on a PowerMac G4, but unless you mention that and the user in question is capable of doing that, it's not a lot of help is it?
Hardware availability? If you can buy it, it's available, right?
Hardware performance - for relevant benchmarks, it depends largely on what the user wants to run.
Hardware quality - Have you measured this? If so, how? If not, why are you mentioning this? Because if you're able to measure scientifically the quality of hardware, I'd really like to know. Also, if such a test existed and worked as it is supposed to, I would be really surprised if a 10-year-old computer was shown to be in a fitter state of health than a brand-new one.
What features the OS has - if it does what the user wants it to do, what's the problem? People buy this because they want to run AmigaOS. There are other solutions which can run AmigaOS, but not many brand-new ones AFAIK.
The level of Amiga compatibility in the OS - repeat previous response.
Amiga standards - repeat previous response.
So, in your "helpful" response on the first page of this thread, how much of this did you convey? Do you think that your initial response help the person asking the question to make a well-educated and informed decision?
To someone who wasn't able to recognise that was a PowerMac G4, that picture conveyed "An X1000 costs 30 PowerMacs". Incredibly helpful.
