none of them have two things that I consider important; redundant power supplies, and Raided hard drives
I don't see the need for redundant PSUs unless absolute, uninterruptible, 24/7/365 uptime is
mission essential. But even then I think a quality UPS with AVR would better serve that purpose and IMO,
EVERY computer should be on a "good" UPS with AVR anyway to ensure the longest life for your computer (and the PSU that powers it). But I don't see one in your list.
Redundant power
WILL take a big chunk out of your budget.
Much more than simply buying a spare PSU to have in ready storage.
I used to be a fan of RAID1 years ago but frankly, HD reliability has improved so significantly, it is an expensive option with little returns. For one, you immediately start by paying
3 times for the same amount of disk space. Yes 3!
RAID1 requires from the start, at least 2 identical drives and since they are mirrored, you already pay twice for the same space. But the purpose of RAID1 is in the event one drive fails, the system will keep on going without a hiccough or loss of data as the mirrored drive takes over. But then what? You only have one drive in there so to restore your array, you need a [preferably identical] 3rd drive sitting in ready storage just waiting to be swapped in - hence 3 times the cost for the same amount of disk space. Since finding an identical drive years after the purchasing the first pair can be a real and expensive challenge, buying all 3 in the beginning is best - yet costly. And what happens if none of the drives fail? You have a perfectly good, brand new, sealed in the anti-static bag HD going unused, potentially for years.
And what does RAID1 really get you? Only immediate redundancy should 1 drive fail. It does not protect you from malware, data corruption, flood, fire, lightning, or a badguy breaking in and stealing your computer.
To me, one good
enterprise class hard drive is what you need, and a good (preferably off-site) backup plan - which you need, regardless.
because of the high costs of software licensing
What software? With that budget, I don't see paying for 2 Windows licenses and 2 Office suite licenses being cost prohibitive. If using some custom application, that can certainly be an issue. But I think you need to see if 2 machines might not still be a better option if full redundancy is a requirement. You can buy a lot of computer for $2K each.
I am NOT saying there is never a need for redundant power and mirrored drives. I am just saying it is important to really weigh the needs to justify the considerable (immediate and long term) costs - keeping in mind that neither provide any significant performance advantages either.